Query Selector Shadow Dom


querySelector that can pierce Shadow DOM roots without knowing the path through nested shadow roots. Useful for automated testing of Web Components e.g. with Selenium, Puppeteer.


// available as an ES6 module for importing in Browser environments

import { querySelectorAllDeep, querySelectorDeep } from 'query-selector-shadow-dom';

What is a nested shadow root?

Image of Shadow DOM elements in dev tools You can see that .dropdown-item:not([hidden]) (Open downloads folder) is several layers deep in shadow roots, most tools will make you do something like

document.querySelector("body > downloads-manager").shadowRoot.querySelector("#toolbar").shadowRoot.querySelector(".dropdown-item:not([hidden])")


with query-selector-shadow-dom:

import { querySelectorAllDeep, querySelectorDeep } from 'query-selector-shadow-dom';


  • querySelectorAllDeep - mirrors querySelectorAll from the browser, will return an Array of elements matching the query
  • querySelectorDeep - mirrors querySelector from the browser, will return the first matching element of the query.
  • collectAllElementsDeep - collects all elements on the page, including shadow dom

Both of the methods above accept a 2nd parameter, see section Provide alternative node. This will change the starting element to search from i.e. it will find ancestors of that node that match the query.

Known limitations

  • Source ordering of results may not be preserved. Due to the nature of how this library works, by breaking down selectors into parts, when using multiple selectors (e.g. split by commas) the results will be based on the order of the query, not the order the result appear in the dom. This is different from the native querySelectorAll functionality. You can read more about this here: https://github.com/Georgegriff/query-selector-shadow-dom/issues/54



This plugin implements a custom selector strategy: https://webdriver.io/docs/selectors.html#custom-selector-strategies

// make sure you have selenium standalone running
const { remote } = require('webdriverio');
const { locatorStrategy } = require('query-selector-shadow-dom/plugins/webdriverio');

(async () => {
    const browser = await remote({
        logLevel: 'error',
        path: '/wd/hub',
        capabilities: {
            browserName: 'chrome'

    // The magic - registry custom strategy
    browser.addLocatorStrategy('shadow', locatorStrategy);

    // now you have a `shadow` custom locator.

    // All elements on the page
    await browser.waitUntil(() => browser.custom$("shadow", ".btn-in-shadow-dom"));
    const elements = await browser.$$("*");

    const elementsShadow = await browser.custom$$("shadow", "*");

    console.log("All Elements on Page Excluding Shadow Dom", elements.length);
    console.log("All Elements on Page Including Shadow Dom", elementsShadow.length);

    await browser.url('')
    // find input element in shadow dom
    const input = await browser.custom$('shadow', '#type-to-input');
    // type to input ! Does not work in firefox, see above.
    await input.setValue('Typed text to input');
    // Firefox workaround
    // await browser.execute((input, val) => input.value = val, input, 'Typed text to input')

    await browser.deleteSession()
})().catch((e) => console.error(e))

How is this different to shadow$

shadow$ only goes one level deep in a shadow root.

Take this example. Image of Shadow DOM elements in dev tools You can see that .dropdown-item:not([hidden]) (Open downloads folder) is several layers deep in shadow roots, but this library will find it, shadow$ would not. You would have to construct a path via css or javascript all the way through to find the right element.

const { remote } = require('webdriverio')
const { locatorStrategy } = require('query-selector-shadow-dom/plugins/webdriverio');

(async () => {
    const browser = await remote({capabilities: {browserName: 'chrome'}})

    browser.addLocatorStrategy('shadow', locatorStrategy);

    await browser.url('chrome://downloads')
    const moreActions = await browser.custom$('shadow', '#moreActions');
    await moreActions.click();
    const span = await browser.custom$('shadow', '.dropdown-item:not([hidden])');
    const text = await span.getText()
    // prints `Open downloads folder`

    await browser.deleteSession()
})().catch((e) => console.error(e))

Known issues


From the above, firefox setValue does NOT currently work. . A workaround for now is to use a custom command (or method on your component object) that sets the input field's value via browser.execute(function).

Safari pretty much doesn't work, not really a surprise.

There are some webdriver examples available in the examples folder of this repository. WebdriverIO examples


Update: As of 5.4.0 Puppeteer now has a built in shadow Dom selector, this module might not be required for Puppeteer anymore. They don't have any documentation: https://github.com/puppeteer/puppeteer/pull/6509

There are some puppeteer examples available in the examples folder of this repository.

Puppeteer examples


Update: as of Playwright v0.14.0 their CSS and text selectors work with shadow Dom out of the box, you don't need this library anymore for Playwright.

Playwright works really nicely with this package.

This module exposes a playwright selectorEngine: https://github.com/microsoft/playwright/blob/main/docs/api.md#selectorsregisterenginefunction-args

const { selectorEngine } = require("query-selector-shadow-dom/plugins/playwright");
const playwright = require('playwright');

 await selectors.register('shadow', createTagNameEngine);
  await page.goto('chrome://downloads');
  // shadow= allows a css query selector that automatically pierces shadow roots.
  await page.waitForSelector('shadow=#no-downloads span', {timeout: 3000})

For a full example see: https://github.com/Georgegriff/query-selector-shadow-dom/blob/main/examples/playwright


This project provides a Protractor plugin, which can be enabled in your protractor.conf.js file:

exports.config = {
    plugins: [{
        package: 'query-selector-shadow-dom/plugins/protractor'
    // ... other Protractor-specific config

The plugin registers a new locator - by.shadowDomCss(selector /* string */), which can be used in regular Protractor tests:


The locator also works with Serenity/JS tests that use Protractor under the hood:

import 'query-selector-shadow-dom/plugins/protractor';
import { Target } from '@serenity-js/protractor'
import { by } from 'protractor';

const ElementOfInterest = Target.the('element of interest')

See the end-to-end tests for more examples.


Provide alternative node

    // query from another node
    querySelectorShadowDom.querySelectorAllDeep('child', document.querySelector('#startNode'));
    // query an iframe
    querySelectorShadowDom.querySelectorAllDeep('child', iframe.contentDocument);

This library does not allow you to query across iframe boundaries, you will need to get a reference to the iframe you want to interact with. 
If your iframe is inside of a shadow root you could cuse querySelectorDeep to find the iframe, then pass the contentDocument into the 2nd argument of querySelectorDeep or querySelectorAllDeep.

Chrome downloads page

In the below examples the components being searched for are nested within web components shadowRoots.

// Download and Paste the lib code in dist into chrome://downloads console to try it out :)

console.log(querySelectorShadowDom.querySelectorAllDeep('downloads-item:nth-child(4) #remove'));
console.log(querySelectorShadowDom.querySelectorAllDeep('#downloads-list .is-active a[href^="https://"]'));
console.log(querySelectorShadowDom.querySelectorDeep('#downloads-list div#title-area + a'));

Shady DOM

If using the polyfills and shady DOM, this library will still work.


  • Shipped as an ES6 module to be included using a bundler of your choice (or not).
  • ES5 version bundled ontop the window as window.querySelectorShadowDom available for easy include into a test framework

Running the code locally

npm install

Running the tests

npm test

Running the tests in watch mode

npm run watch

Running the build

npm run build

Author: Georgegriff
Source Code: https://github.com/Georgegriff/query-selector-shadow-dom 
License: MIT license

#node #javascript #webdriver #webcomponents 

What is GEEK

Buddha Community

Query Selector Shadow Dom
Corey Brooks

Corey Brooks


Top 9+ Common CSS Mistakes To Avoid

In this tutorial, we'll summarise what the top 9+ CSS mistakes are and how to avoid them.

Top 9+ Common CSS Mistakes To Avoid

It’s easy to get tripped up with CSS. Here are some common CSS mistakes we all make.

1. Not Using a Proper CSS Reset

Web browsers are our fickle friends. Their inconsistencies can make any developer want to tear their hair out. But at the end of the day, they’re what will present your website, so you better do what you have to do to please them.

One of the sillier things browsers do is provide default styling for HTML elements. I suppose you can’t really blame them: what if a “webmaster” chose not to style their page? There has to be a fallback mechanism for people who choose not to use CSS.

In any case, there’s rarely a case of two browsers providing identical default styling, so the only real way to make sure your styles are effective is to use a CSS reset. What a CSS reset entails is resetting (or, rather, setting) all the styles of all the HTML elements to a predictable baseline value. The beauty of this is that once you include a CSS reset effectively, you can style all the elements on your page as if they were all the same to start with.

It’s a blank slate, really. There are many CSS reset codebases on the web that you can incorporate into your work. I personally use a modified version of the popular Eric Meyer reset and Six Revisions uses a modified version of YUI Reset CSS.

You can also build your own reset if you think it would work better. What many of us do is utilizing a simple universal selector margin/padding reset.

* { margin:0; padding:0; } 

Though this works, it’s not a full reset.

You also need to reset, for example, borders, underlines, and colors of elements like list items, links, and tables so that you don’t run into unexpected inconsistencies between web browsers. Learn more about resetting your styles via this guide: Resetting Your Styles with CSS Reset.

2. Over-Qualifying Selectors

Being overly specific when selecting elements to style is not good practice. The following selector is a perfect example of what I’m talking about:

ul#navigation li a { ... } 

Typically the structure of a primary navigation list is a <ul> (usually with an ID like #nav or #navigation) then a few list items (<li>) inside of it, each with its own <a> tag inside it that links to other pages.

This HTML structure is perfectly correct, but the CSS selector is really what I’m worried about. First things first: There’s no reason for the ul before #navigation as an ID is already the most specific selector. Also, you don’t have to put li in the selector syntax because all the a elements inside the navigation are inside list items, so there’s no reason for that bit of specificity.

Thus, you can condense that selector as:

#navigation a { ... } 

This is an overly simplistic example because you might have nested list items that you want to style differently (i.e. #navigation li a is different from #navigation li ul li a); but if you don’t, then there’s no need for the excessive specificity.

I also want to talk about the need for an ID in this situation. Let’s assume for a minute that this navigation list is inside a header div (#header). Let us also assume that you will have no other unordered list in the header besides the navigation list.

If that is the case, we can even remove the ID from the unordered list in our HTML markup, and then we can select it in CSS as such:

#header ul a { ... } 

Here’s what I want you to take away from this example: Always write your CSS selectors with the very minimum level of specificity necessary for it to work. Including all that extra fluff may make it look more safe and precise, but when it comes to CSS selectors, there are only two levels of specificity: specific, and not specific enough.

3. Not Using Shorthand Properties

Take a look at the following property list:

#selector { margin-top: 50px; margin-right: 0; margin-bottom: 50px; margin-left 0; }

What is wrong with this picture? I hope that alarm bells are ringing in your head as you notice how much we’re repeating ourselves. Fortunately, there is a solution, and it’s using CSS shorthand properties.

The following has the same effect as the above style declaration, but we’ve reduced our code by three lines.

#selector { margin: 50px 0; }

Check out this list of properties that deals with font styles:

font-family: Helvetica; font-size: 14px; font-weight: bold; line-height: 1.5;

We can condense all that into one line:

font: bold 14px/1.5 Helvetica; 

We can also do this for background properties. The following:

background-image: url(background.png); background-repeat: repeat-y; background-position: center top;

Can be written in shorthand CSS as such:

background: url(background.png) repeat-y center top; 

4. Using 0px instead of 0

Say you want to add a 20px margin to the bottom of an element. You might use something like this:

#selector { margin: 20px 0px 20px 0px; } 

Don’t. This is excessive.

There’s no need to include the px after 0. While this may seem like I’m nitpicking and that it may not seem like much, when you’re working with a huge file, removing all those superfluous px can reduce the size of your file (which is never a bad thing).

5. Using Color Names Instead of Hexadecimal

Declaring red for color values is the lazy man’s #FF0000. By saying:

color: red;

You’re essentially saying that the browser should display what it thinks red is. If you’ve learned anything from making stuff function correctly in all browsers — and the hours of frustration you’ve accumulated because of a stupid list-bullet misalignment that can only be seen in IE7 — it’s that you should never let the browser decide how to display your web pages.

Instead, you should go to the effort to find the actual hex value for the color you’re trying to use. That way, you can make sure it’s the same color displayed across all browsers. You can use a color cheatsheet that provides a preview and the hex value of a color.

This may seem trivial, but when it comes to CSS, it’s the tiny things that often lead to the big gotchas.

6. Redundant Selectors

My process for writing styles is to start with all the typography, and then work on the structure, and finally on styling all the colors and backgrounds. That’s what works for me. Since I don’t focus on just one element at a time, I commonly find myself accidentally typing out a redundant style declaration.

I always do a final check after I’m done so that I can make sure that I haven’t repeated any selectors; and if I have, I’ll merge them. This sort of mistake is fine to make while you’re developing, but just try to make sure they don’t make it into production.

7. Redundant Properties

Similar to the one above, I often find myself having to apply the same properties to multiple selectors. This could be styling an <h5> in the header to look exactly like the <h6> in the footer, making the <pre>‘s and <blockquote>‘s the same size, or any number of things in between. In the final review of my CSS, I will look to make sure that I haven’t repeated too many properties.

For example, if I see two selectors doing the same thing, such as this:

#selector-1 { font-style: italic; color: #e7e7e7; margin: 5px; padding: 20px } .selector-2 { font-style: italic; color: #e7e7e7; margin: 5px; padding: 20px }

I will combine them, with the selectors separated by a comma (,):

#selector-1, .selector-2 { font-style: italic; color: #e7e7e7; margin: 5px; padding: 20px }

I hope you’re seeing the trend here: Try to be as terse and as efficient as possible. It pays dividends in maintenance time and page-load speed.

8. Not Providing Fallback Fonts

In a perfect world, every computer would always have every font you would ever want to use installed. Unfortunately, we don’t live in a perfect world. @font-face aside, web designers are pretty much limited to the few so called web-safe fonts (e.g.

Arial, Georgia, serif, etc.). There is a plus side, though. You can still use fonts like Helvetica that aren’t necessarily installed on every computer.

The secret lies in font stacks. Font stacks are a way for developers to provide fallback fonts for the browser to display if the user doesn’t have the preferred font installed. For example:

#selector { font-family: Helvetica; }

Can be expanded with fallback fonts as such:

#selector { font-family: Helvetica, Arial, sans-serif; }

Now, if the user doesn’t have Helvetica, they can see your site in Arial, and if that doesn’t work, it’ll just default to any sans-serif font installed.

By defining fallback fonts, you gain more control as to how your web pages are rendered.

9. Unnecessary Whitespace

When it comes to trying to reduce your CSS file sizes for performance, every space counts. When you’re developing, it’s OK to format your code in the way that you’re comfortable with. However, there is absolutely no reason not to take out excess characters (a process known as minification) when you actually push your project onto the web where the size of your files really counts.

Too many developers simply don’t minify their files before launching their websites, and I think that’s a huge mistake. Although it may not feel like it makes much of a difference, when you have huge CSS files

10. Not Organizing Your CSS in a Logical Way

When you’re writing CSS, do yourself a favor and organize your code. Through comments, you can insure that the next time you come to make a change to a file you’ll still be able to navigate it. 

I personally like to organize my styles by how the HTML that I’m styling is structured. This means that I have comments that distinguish the header, body, sidebar, and footer. A common CSS-authoring mistake I see is people just writing up their styles as soon as they think of them.

The next time you try to change something and can’t find the style declaration, you’ll be silently cursing yourself for not organizing your CSS well enough.

11. Using Only One Stylesheet for Everything

This one’s subjective, so bear with me while I give you my perspective. I am of the belief, as are others, that it is better to split stylesheets into a few different ones for big sites for easier maintenance and for better modularity. Maybe I’ll have one for a CSS reset, one for IE-specific fixes, and so on.

By organizing CSS into disparate stylesheets, I’ll know immediately where to find a style I want to change. You can do this by importing all the stylesheets into a stylesheet like so:

@import url("reset.css"); @import url("ie.css"); @import url("typography.css"); @import url("layout.css"); 

Let me stress, however, that this is what works for me and many other developers. You may prefer to squeeze them all in one file, and that’s okay; there’s nothing wrong with that.

But if you’re having a hard time maintaining a single file, try splitting your CSS up.

12. Not Providing a Print Stylesheet

In order to style your site on pages that will be printed, all you have to do is utilize and include a print stylesheet. It’s as easy as:

<link rel="stylesheet" href="print.css" media="print" /> 

Using a stylesheet for print allows you to hide elements you don’t want printed (such as your navigation menu), reset the background color to white, provide alternative typography for paragraphs so that it’s better suited on a piece of paper, and so forth. The important thing is that you think about how your page will look when printed.

Too many people just don’t think about it, so their sites will simply print the same way you see them on the screen.

I Made These 2 BEGINNER CSS Mistakes

No matter how long you've been writing code, it's always a good time to revisit the basics. While working on a project the other day, I made 2 beginner mistakes with the CSS I was writing. I misunderstood both CSS specificity and how transform:scale affects the DOM!

Stack Overflow about transform:scale - https://stackoverflow.com/questions/32835144/css-transform-scale-does-not-change-dom-size 
CSS Specificity - https://www.w3schools.com/css/css_specificity.asp 


Roscoe  Batz

Roscoe Batz


SwiftIcons: Swift Library for Font Icons

Swift Library for Font Icons

Please ★ this library.

Now, you don't have to download different libraries to include different font icons. This SwiftIcons library helps you use icons from any of the following font icons.

  • Dripicons
  • Emoji
  • FontAwesome
  • Icofont
  • Ionicons
  • Linearicons
  • Map-icons
  • Material icons
  • Open iconic
  • State face icons
  • Weather icons
  • TypIcons

SwiftIcons supports different objects from the object library.

  • UIImage
  • UIImageView
  • UILabel
  • UIButton
  • UISegmentedControl
  • UITabBarItem
  • UISlider
  • UIBarButtonItem
  • UIViewController
  • UITextfield
  • UIStepper


  • iOS 9.0+
  • Xcode 8



CocoaPods is a dependency manager for Cocoa projects.

Make sure you have the latest version of CocoaPods by running:

$ gem install cocoapods
# (or if the above fails)
$ sudo gem install cocoapods

Update your local specs repo by running:

$ pod repo update

Add the following lines to your Podfile:

target 'YourProject' do
    pod 'SwiftIcons', '~> 3.0'

Then run the following command

$ pod install

You can start using the library by importing it wherever you want

import SwiftIcons


Carthage is a decentralized dependency manager for Cocoa projects.

Install the latest version of Carthage.

Add this line to your Cartfile:

github "ranesr/SwiftIcons" ~> 3.0

or for master,

github "ranesr/SwiftIcons" "master"

Then run carthage update --platform ios and add the built framework to your project by following these instructions from Carthage.


Copy all the files from Source folder. Link to files.

  • SwiftIcons.swift
  • Dripicons.ttf
  • Emoji.ttf
  • FontAwesomeBrands.ttf
  • FontAwesomeRegular.ttf
  • FontAwesomeSolid.ttf
  • Icofont.ttf
  • Ionicons.ttf
  • Linearicons.ttf
  • MapIcons.ttf
  • MaterialIcons.ttf
  • OpenIconic.ttf
  • Stateface.ttf
  • WeatherIcons.ttf
  • TypIcons.ttf

Check to import all ttf files in project, "Project" > "Target" > "Copy Bundle Resources"

Library Reference

You can check library reference documentation here.


  • No more image icons any more

There are different font types for each of the font icons

Font IconsVersionFont TypesIcons
Emoji emojiemoji
Icofont1.0.0 Betaicofonticofont
Material icons2.2.0googleMaterialDesigngoogleMaterialDesign
Open iconic1.1.1openIconicopenIconic
State face icons statestate
Weather icons2.0.10weatherweather

When setting an icon to any object, you have to mention which font type it is and then select which icon you want to set from that particular font icon.


import SwiftIcons

UIImage.init(icon: .emoji(.airplane), size: CGSize(width: 35, height: 35))

// Icon with colors
UIImage.init(icon: .emoji(.airplane), size: CGSize(width: 35, height: 35), textColor: .red)
UIImage.init(icon: .emoji(.airplane), size: CGSize(width: 35, height: 35), textColor: .white, backgroundColor: .red)

// Stacked icons with bigger background
UIImage.init(bgIcon: .fontAwesomeRegular(.circle), topIcon: .fontAwesomeRegular(.square))

// Stacked icons with smaller background
UIImage.init(bgIcon: .fontAwesomeSolid(.camera), topIcon: .fontAwesomeSolid(.ban), topTextColor: .red, bgLarge: false)

// Stacked icons with custom size
UIImage.init(bgIcon: .fontAwesomeSolid(.camera), topIcon: .fontAwesomeSolid(.ban), topTextColor: .red, bgLarge: false, size: CGSize(width: 50, height: 50))


import SwiftIcons

// Setting icon to image view
imageView.setIcon(icon: .weather(.rainMix))

// Icon with colors
imageView.setIcon(icon: .mapicons(.amusementPark), textColor: .white, backgroundColor: .blue, size: nil)


import SwiftIcons

// Setting icon to label
label.setIcon(icon: .ionicons(.paintbrush), iconSize: 70)

// Icon with colors
label.setIcon(icon: .googleMaterialDesign(.rowing), iconSize: 70, color: .white, bgColor: textColor)

// Icon with text around it
label.setIcon(prefixText: "Bus ", icon: .linearIcons(.bus), postfixText: " icon", size: 20)

// Icon with color & colored text around it
label.setIcon(prefixText: "Medal ", prefixTextColor: .red, icon: .ionicons(.ribbonA), iconColor: .red, postfixText: "", postfixTextColor: .red, size: nil, iconSize: 40)

// Icon with text with different fonts around it
label.setIcon(prefixText: "Font ", prefixTextFont: font1!, icon: .fontAwesomeSolid(.font), postfixText: " icon", postfixTextFont: font2!)

// Icon with text with different fonts & colors around it
label.setIcon(prefixText: "Bike ", prefixTextFont: font1!, prefixTextColor: .red, icon: .mapicons(.bicycling), iconColor: textColor, postfixText: " icon", postfixTextFont: font2!, postfixTextColor: .blue, iconSize: 30)


import SwiftIcons

// Setting icon to button
button.setIcon(icon: .linearIcons(.phone), forState: .normal)

// Icon with size and color
button.setIcon(icon: .openIconic(.clipboard), iconSize: 70, color: .blue, forState: .normal)

// Icon with text around it
button.setIcon(prefixText: "Please ", icon: .googleMaterialDesign(.print), postfixText: " print", forState: .normal)

// Icon with color & colored text around it
button.setIcon(prefixText: "Lock ", prefixTextColor: .red, icon: .googleMaterialDesign(.lock), iconColor: .yellow, postfixText: " icon", postfixTextColor: .blue, forState: .normal, textSize: 15, iconSize: 20)

// Icon with text with different fonts around it
button.setIcon(prefixText: "Happy ", prefixTextFont: font1!, icon: .ionicons(.happy), postfixText: " face", postfixTextFont: font2!, forState: .normal)

// Icon with text with different fonts & colors around it
button.setIcon(prefixText: "Pulse ", prefixTextFont: font1!, prefixTextColor: .darkGray, icon: .openIconic(.pulse), iconColor: .red, postfixText: " icon", postfixTextFont: font2!, postfixTextColor: .purple, forState: .normal, iconSize: 40)

// Icon with title below icon
button.setIcon(icon: .emoji(.ferrisWheel), title: "Ferris Wheel", color: .red, forState: .normal)

// Icon with title below icon with different color & custom font
button.setIcon(icon: .weather(.rainMix), iconColor: .yellow, title: "RAIN MIX", titleColor: .red, font: font!, backgroundColor: .clear, borderSize: 1, borderColor: .green, forState: .normal)


import SwiftIcons

// Setting icon at particular index
segmentedControl.setIcon(icon: .linearIcons(.thumbsUp), forSegmentAtIndex: 0)
segmentedControl.setIcon(icon: .linearIcons(.thumbsDown), forSegmentAtIndex: 1)

// Icons with sizes & colors
segmentedControl.setIcon(icon: .fontAwesomeSolid(.male), color: .red, iconSize: 50, forSegmentAtIndex: 0)
segmentedControl.setIcon(icon: .fontAwesomeSolid(.female), color: .purple, iconSize: 50, forSegmentAtIndex: 1)


import SwiftIcons

// Setting icon to tab bar item
tabBar.items?[0].setIcon(icon: .fontAwesomeSolid(.font), size: nil, textColor: .lightGray)

// Stacked icons for tab bar item
tabBar.items?[1].setIcon(bgIcon: .fontAwesomeRegular(.circle), bgTextColor: .lightGray, topIcon: .fontAwesomeSolid(.square), topTextColor: .lightGray, bgLarge: true, size: nil)


import SwiftIcons

// Change minimum & maximum value icons
slider.setMaximumValueIcon(icon: .emoji(.digitNine))
slider.setMinimumValueIcon(icon: .emoji(.digitZero))

// Change minimum & maximum value icons with colors
slider.setMaximumValueIcon(icon: .linearIcons(.pointerUp), customSize: nil, textColor: .red, backgroundColor: .clear)
slider.setMinimumValueIcon(icon: .linearIcons(.pointerDown), customSize: nil, textColor: .blue, backgroundColor: .clear)


import SwiftIcons

// Setting icon to bar button item
barButtonItem.setIcon(icon: .ionicons(.iosFootball), iconSize: 30)

// Icon with colors
barButtonItem.setIcon(icon: .ionicons(.iosFootball), iconSize: 30, color: textColor)

// Icon with custom cgRect
barButtonItem.setIcon(icon: .ionicons(.iosFootball), iconSize: 30, color: textColor, cgRect: CGRect(x: 0, y: 0, width: 30, height: 30), target: self, action: #selector(barButtonItem(sender:)))

// Icon with text around it
barButtonItem.setIcon(prefixText: "Please ", icon: .ionicons(.iosDownload), postfixText: " download", cgRect: CGRect(x: 0, y: 0, width: 30, height: 30), size: 23, target: self, action: #selector(barButtonItem(sender:)))

// Icon with color & colored text around it
barButtonItem.setIcon(prefixText: "Blue ", prefixTextColor: .red, icon: .ionicons(.iosFootball), iconColor: .blue, postfixText: " football", postfixTextColor: .green, cgRect: CGRect(x: 0, y: 0, width: 30, height: 30), size: 20, iconSize: 30, target: self, action: #selector(barButtonItem(sender:)))

// Icon with text with different fonts around it
barButtonItem.setIcon(prefixText: "Digit ", prefixTextFont: font1!, icon: .emoji(.digitOne), postfixText: " One", postfixTextFont: font2!, cgRect: CGRect(x: 0, y: 0, width: 30, height: 30), target: self, action: #selector(barButtonItem(sender:)))

// Icon with text with different fonts & colors around it
barButtonItem.setIcon(prefixText: "", prefixTextFont: font1!, prefixTextColor: .red, icon: .ionicons(.iosFootball), iconColor: .blue, postfixText: " football", postfixTextFont: font2!, postfixTextColor: .green, cgRect: CGRect(x: 0, y: 0, width: 30, height: 30), iconSize: 24, target: self, action: #selector(barButtonItem(sender:)))


import SwiftIcons

// Setting icon to the title
self.setTitleIcon(icon: .emoji(.animalHorse), iconSize: 30, color: .red)


import SwiftIcons

// Setting left view icon
textfield.setLeftViewIcon(icon: .fontAwesomeSolid(.search))

// Left view icon with colors & leftViewMode
textfield.setLeftViewIcon(icon: .state(.TX), leftViewMode: .always, textColor: .blue, backgroundColor: .clear, size: nil)
textfield.setLeftViewIcon(icon: .googleMaterialDesign(.plusOne), leftViewMode: .unlessEditing, textColor: .green, backgroundColor: .clear, size: nil)

// Setting right view icon
textfield.setRightViewIcon(icon: .openIconic(.questionMark))

// Right view icon with colors & rightViewMode
textfield.setRightViewIcon(icon: .weather(.rainMix), rightViewMode: .always, textColor: .red, backgroundColor: .clear, size: nil)


import SwiftIcons

// Setting icons
stepper.setDecrementIcon(icon: .ionicons(.iosPause), forState: .normal)
stepper.setIncrementIcon(icon: .ionicons(.iosPlay), forState: .normal)


Please check out the SwiftIcons App. In the demo project, if you click on any object, you will see the method description in the logs for the icon of that object.

SwiftIcons Mentions & Usage

If you are using SwiftIcons in your app and want to be listed here, simply create a new issue here.

I am always curious who is using my projects 😊


Saurabh Rane

Special thanks to Patrik Vaberer and his initial work on Font-Awesome-Swift library

Download Details:

Author: ranesr
Source code: https://github.com/ranesr/SwiftIcons

License: MIT license

What is DOM, Shadow DOM and Virtual DOM?

In this lesson, we learn about the Document Object Model. We learn what the DOM, Shadow DOM, and Virtual DOM are and how they work. We also look at some of the practical examples to understand them better.

#dom #shadow dom #virtual dom

Ahebwe  Oscar

Ahebwe Oscar


How model queries work in Django

How model queries work in Django

Welcome to my blog, hey everyone in this article we are going to be working with queries in Django so for any web app that you build your going to want to write a query so you can retrieve information from your database so in this article I’ll be showing you all the different ways that you can write queries and it should cover about 90% of the cases that you’ll have when you’re writing your code the other 10% depend on your specific use case you may have to get more complicated but for the most part what I cover in this article should be able to help you so let’s start with the model that I have I’ve already created it.

**Read More : **How to make Chatbot in Python.

Read More : Django Admin Full Customization step by step

let’s just get into this diagram that I made so in here:

django queries aboutDescribe each parameter in Django querset

we’re making a simple query for the myModel table so we want to pull out all the information in the database so we have this variable which is gonna hold a return value and we have our myModel models so this is simply the myModel model name so whatever you named your model just make sure you specify that and we’re gonna access the objects attribute once we get that object’s attribute we can simply use the all method and this will return all the information in the database so we’re gonna start with all and then we will go into getting single items filtering that data and go to our command prompt.

Here and we’ll actually start making our queries from here to do this let’s just go ahead and run** Python manage.py shell** and I am in my project file so make sure you’re in there when you start and what this does is it gives us an interactive shell to actually start working with our data so this is a lot like the Python shell but because we did manage.py it allows us to do things a Django way and actually query our database now open up the command prompt and let’s go ahead and start making our first queries.

#django #django model queries #django orm #django queries #django query #model django query #model query #query with django

Daron  Moore

Daron Moore


Raywenderlich: The Official Raywenderlich.com Swift Style Guide

The Official raywenderlich.com Swift Style Guide.

Updated for Swift 5

This style guide is different from others you may see, because the focus is centered on readability for print and the web. We created this style guide to keep the code in our books, tutorials, and starter kits nice and consistent — even though we have many different authors working on the books.

Our overarching goals are clarity, consistency and brevity, in that order.


Strive to make your code compile without warnings. This rule informs many style decisions such as using #selector types instead of string literals.

Using SwiftLint

When writing for raywenderlich.com, you are strongly encouraged — and some teams may require — to use our SwiftLint configuration. See the SwiftLint Policy for more information.


Descriptive and consistent naming makes software easier to read and understand. Use the Swift naming conventions described in the API Design Guidelines. Some key takeaways include:

  • striving for clarity at the call site
  • prioritizing clarity over brevity
  • using camelCase (not snake_case)
  • using UpperCamelCase for types and protocols, lowerCamelCase for everything else
  • including all needed words while omitting needless words
  • using names based on roles, not types
  • sometimes compensating for weak type information
  • striving for fluent usage
  • beginning factory methods with make
  • naming methods for their side effects
    • verb methods follow the -ed, -ing rule for the non-mutating version
    • noun methods follow the formX rule for the mutating version
    • boolean types should read like assertions
    • protocols that describe what something is should read as nouns
    • protocols that describe a capability should end in -able or -ible
  • using terms that don't surprise experts or confuse beginners
  • generally avoiding abbreviations
  • using precedent for names
  • preferring methods and properties to free functions
  • casing acronyms and initialisms uniformly up or down
  • giving the same base name to methods that share the same meaning
  • avoiding overloads on return type
  • choosing good parameter names that serve as documentation
  • preferring to name the first parameter instead of including its name in the method name, except as mentioned under Delegates
  • labeling closure and tuple parameters
  • taking advantage of default parameters


When referring to methods in prose, being unambiguous is critical. To refer to a method name, use the simplest form possible.

  1. Write the method name with no parameters. Example: Next, you need to call addTarget.
  2. Write the method name with argument labels. Example: Next, you need to call addTarget(_:action:).
  3. Write the full method name with argument labels and types. Example: Next, you need to call addTarget(_: Any?, action: Selector?).

For the above example using UIGestureRecognizer, 1 is unambiguous and preferred.

Pro Tip: You can use Xcode's jump bar to lookup methods with argument labels. If you’re particularly good at mashing lots of keys simultaneously, put the cursor in the method name and press Shift-Control-Option-Command-C (all 4 modifier keys) and Xcode will kindly put the signature on your clipboard.

Methods in Xcode jump bar

Class Prefixes

Swift types are automatically namespaced by the module that contains them and you should not add a class prefix such as RW. If two names from different modules collide you can disambiguate by prefixing the type name with the module name. However, only specify the module name when there is possibility for confusion, which should be rare.

import SomeModule let myClass = MyModule.UsefulClass()


When creating custom delegate methods, an unnamed first parameter should be the delegate source. (UIKit contains numerous examples of this.)


func namePickerView(_ namePickerView: NamePickerView, didSelectName name: String)
func namePickerViewShouldReload(_ namePickerView: NamePickerView) -> Bool

Not Preferred:

func didSelectName(namePicker: NamePickerViewController, name: String)
func namePickerShouldReload() -> Bool

Use Type Inferred Context

Use compiler inferred context to write shorter, clear code. (Also see Type Inference.)


let selector = #selector(viewDidLoad)
view.backgroundColor = .red
let toView = context.view(forKey: .to)
let view = UIView(frame: .zero)

Not Preferred:

let selector = #selector(ViewController.viewDidLoad)
view.backgroundColor = UIColor.red
let toView = context.view(forKey: UITransitionContextViewKey.to)
let view = UIView(frame: CGRect.zero)


Generic type parameters should be descriptive, upper camel case names. When a type name doesn't have a meaningful relationship or role, use a traditional single uppercase letter such as T, U, or V.


struct Stack<Element> { ... }
func write<Target: OutputStream>(to target: inout Target)
func swap<T>(_ a: inout T, _ b: inout T)

Not Preferred:

struct Stack<T> { ... }
func write<target: OutputStream>(to target: inout target)
func swap<Thing>(_ a: inout Thing, _ b: inout Thing)


Use US English spelling to match Apple's API.


let color = "red"

Not Preferred:

let colour = "red"

Code Organization

Use extensions to organize your code into logical blocks of functionality. Each extension should be set off with a // MARK: - comment to keep things well-organized.

Protocol Conformance

In particular, when adding protocol conformance to a model, prefer adding a separate extension for the protocol methods. This keeps the related methods grouped together with the protocol and can simplify instructions to add a protocol to a class with its associated methods.


class MyViewController: UIViewController {
  // class stuff here

// MARK: - UITableViewDataSource
extension MyViewController: UITableViewDataSource {
  // table view data source methods

// MARK: - UIScrollViewDelegate
extension MyViewController: UIScrollViewDelegate {
  // scroll view delegate methods

Not Preferred:

class MyViewController: UIViewController, UITableViewDataSource, UIScrollViewDelegate {
  // all methods

Since the compiler does not allow you to re-declare protocol conformance in a derived class, it is not always required to replicate the extension groups of the base class. This is especially true if the derived class is a terminal class and a small number of methods are being overridden. When to preserve the extension groups is left to the discretion of the author.

For UIKit view controllers, consider grouping lifecycle, custom accessors, and IBAction in separate class extensions.

Unused Code

Unused (dead) code, including Xcode template code and placeholder comments should be removed. An exception is when your tutorial or book instructs the user to use the commented code.

Aspirational methods not directly associated with the tutorial whose implementation simply calls the superclass should also be removed. This includes any empty/unused UIApplicationDelegate methods.


override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
  return Database.contacts.count

Not Preferred:

override func didReceiveMemoryWarning() {
  // Dispose of any resources that can be recreated.

override func numberOfSections(in tableView: UITableView) -> Int {
  // #warning Incomplete implementation, return the number of sections
  return 1

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
  // #warning Incomplete implementation, return the number of rows
  return Database.contacts.count

Minimal Imports

Import only the modules a source file requires. For example, don't import UIKit when importing Foundation will suffice. Likewise, don't import Foundation if you must import UIKit.


import UIKit
var view: UIView
var deviceModels: [String]


import Foundation
var deviceModels: [String]

Not Preferred:

import UIKit
import Foundation
var view: UIView
var deviceModels: [String]

Not Preferred:

import UIKit
var deviceModels: [String]


  • Indent using 2 spaces rather than tabs to conserve space and help prevent line wrapping. Be sure to set this preference in Xcode and in the Project settings as shown below:

Xcode indent settings

  • Method braces and other braces (if/else/switch/while etc.) always open on the same line as the statement but close on a new line.
  • Tip: You can re-indent by selecting some code (or Command-A to select all) and then Control-I (or Editor ▸ Structure ▸ Re-Indent in the menu). Some of the Xcode template code will have 4-space tabs hard coded, so this is a good way to fix that.


if user.isHappy {
  // Do something
} else {
  // Do something else

Not Preferred:

if user.isHappy
  // Do something
else {
  // Do something else

There should be one blank line between methods and up to one blank line between type declarations to aid in visual clarity and organization. Whitespace within methods should separate functionality, but having too many sections in a method often means you should refactor into several methods.

There should be no blank lines after an opening brace or before a closing brace.

Closing parentheses should not appear on a line by themselves.


let user = try await getUser(
  for: userID,
  on: connection)

Not Preferred:

let user = try await getUser(
  for: userID,
  on: connection
  • Colons always have no space on the left and one space on the right. Exceptions are the ternary operator ? :, empty dictionary [:] and #selector syntax addTarget(_:action:).


class TestDatabase: Database {
  var data: [String: CGFloat] = ["A": 1.2, "B": 3.2]

Not Preferred:

class TestDatabase : Database {
  var data :[String:CGFloat] = ["A" : 1.2, "B":3.2]

Long lines should be wrapped at around 70 characters. A hard limit is intentionally not specified.

Avoid trailing whitespaces at the ends of lines.

Add a single newline character at the end of each file.


When they are needed, use comments to explain why a particular piece of code does something. Comments must be kept up-to-date or deleted.

Avoid block comments inline with code, as the code should be as self-documenting as possible. Exception: This does not apply to those comments used to generate documentation.

Avoid the use of C-style comments (/* ... */). Prefer the use of double- or triple-slash.

Classes and Structures

Which one to use?

Remember, structs have value semantics. Use structs for things that do not have an identity. An array that contains [a, b, c] is really the same as another array that contains [a, b, c] and they are completely interchangeable. It doesn't matter whether you use the first array or the second, because they represent the exact same thing. That's why arrays are structs.

Classes have reference semantics. Use classes for things that do have an identity or a specific life cycle. You would model a person as a class because two person objects are two different things. Just because two people have the same name and birthdate, doesn't mean they are the same person. But the person's birthdate would be a struct because a date of 3 March 1950 is the same as any other date object for 3 March 1950. The date itself doesn't have an identity.

Sometimes, things should be structs but need to conform to AnyObject or are historically modeled as classes already (NSDate, NSSet). Try to follow these guidelines as closely as possible.

Example definition

Here's an example of a well-styled class definition:

class Circle: Shape {
  var x: Int, y: Int
  var radius: Double
  var diameter: Double {
    get {
      return radius * 2
    set {
      radius = newValue / 2

  init(x: Int, y: Int, radius: Double) {
    self.x = x
    self.y = y
    self.radius = radius

  convenience init(x: Int, y: Int, diameter: Double) {
    self.init(x: x, y: y, radius: diameter / 2)

  override func area() -> Double {
    return Double.pi * radius * radius

extension Circle: CustomStringConvertible {
  var description: String {
    return "center = \(centerString) area = \(area())"
  private var centerString: String {
    return "(\(x),\(y))"

The example above demonstrates the following style guidelines:

  • Specify types for properties, variables, constants, argument declarations and other statements with a space after the colon but not before, e.g. x: Int, and Circle: Shape.
  • Define multiple variables and structures on a single line if they share a common purpose / context.
  • Indent getter and setter definitions and property observers.
  • Don't add modifiers such as internal when they're already the default. Similarly, don't repeat the access modifier when overriding a method.
  • Organize extra functionality (e.g. printing) in extensions.
  • Hide non-shared, implementation details such as centerString inside the extension using private access control.

Use of Self

For conciseness, avoid using self since Swift does not require it to access an object's properties or invoke its methods.

Use self only when required by the compiler (in @escaping closures, or in initializers to disambiguate properties from arguments). In other words, if it compiles without self then omit it.

Computed Properties

For conciseness, if a computed property is read-only, omit the get clause. The get clause is required only when a set clause is provided.


var diameter: Double {
  return radius * 2

Not Preferred:

var diameter: Double {
  get {
    return radius * 2


Marking classes or members as final in tutorials can distract from the main topic and is not required. Nevertheless, use of final can sometimes clarify your intent and is worth the cost. In the below example, Box has a particular purpose and customization in a derived class is not intended. Marking it final makes that clear.

// Turn any generic type into a reference type using this Box class.
final class Box<T> {
  let value: T
  init(_ value: T) {
    self.value = value

Function Declarations

Keep short function declarations on one line including the opening brace:

func reticulateSplines(spline: [Double]) -> Bool {
  // reticulate code goes here

For functions with long signatures, put each parameter on a new line and add an extra indent on subsequent lines:

func reticulateSplines(
  spline: [Double], 
  adjustmentFactor: Double,
  translateConstant: Int, 
  comment: String
) -> Bool {
  // reticulate code goes here

Don't use (Void) to represent the lack of an input; simply use (). Use Void instead of () for closure and function outputs.


func updateConstraints() -> Void {
  // magic happens here

typealias CompletionHandler = (result) -> Void

Not Preferred:

func updateConstraints() -> () {
  // magic happens here

typealias CompletionHandler = (result) -> ()

Function Calls

Mirror the style of function declarations at call sites. Calls that fit on a single line should be written as such:

let success = reticulateSplines(splines)

If the call site must be wrapped, put each parameter on a new line, indented one additional level:

let success = reticulateSplines(
  spline: splines,
  adjustmentFactor: 1.3,
  translateConstant: 2,
  comment: "normalize the display")

Closure Expressions

Use trailing closure syntax only if there's a single closure expression parameter at the end of the argument list. Give the closure parameters descriptive names.


UIView.animate(withDuration: 1.0) {
  self.myView.alpha = 0

UIView.animate(withDuration: 1.0, animations: {
  self.myView.alpha = 0
}, completion: { finished in

Not Preferred:

UIView.animate(withDuration: 1.0, animations: {
  self.myView.alpha = 0

UIView.animate(withDuration: 1.0, animations: {
  self.myView.alpha = 0
}) { f in

For single-expression closures where the context is clear, use implicit returns:

attendeeList.sort { a, b in
  a > b

Chained methods using trailing closures should be clear and easy to read in context. Decisions on spacing, line breaks, and when to use named versus anonymous arguments is left to the discretion of the author. Examples:

let value = numbers.map { $0 * 2 }.filter { $0 % 3 == 0 }.index(of: 90)

let value = numbers
  .map {$0 * 2}
  .filter {$0 > 50}
  .map {$0 + 10}


Always use Swift's native types and expressions when available. Swift offers bridging to Objective-C so you can still use the full set of methods as needed.


let width = 120.0                                    // Double
let widthString = "\(width)"                         // String

Less Preferred:

let width = 120.0                                    // Double
let widthString = (width as NSNumber).stringValue    // String

Not Preferred:

let width: NSNumber = 120.0                          // NSNumber
let widthString: NSString = width.stringValue        // NSString

In drawing code, use CGFloat if it makes the code more succinct by avoiding too many conversions.


Constants are defined using the let keyword and variables with the var keyword. Always use let instead of var if the value of the variable will not change.

Tip: A good technique is to define everything using let and only change it to var if the compiler complains!

You can define constants on a type rather than on an instance of that type using type properties. To declare a type property as a constant simply use static let. Type properties declared in this way are generally preferred over global constants because they are easier to distinguish from instance properties. Example:


enum Math {
  static let e = 2.718281828459045235360287
  static let root2 = 1.41421356237309504880168872

let hypotenuse = side * Math.root2

Note: The advantage of using a case-less enumeration is that it can't accidentally be instantiated and works as a pure namespace.

Not Preferred:

let e = 2.718281828459045235360287  // pollutes global namespace
let root2 = 1.41421356237309504880168872

let hypotenuse = side * root2 // what is root2?

Static Methods and Variable Type Properties

Static methods and type properties work similarly to global functions and global variables and should be used sparingly. They are useful when functionality is scoped to a particular type or when Objective-C interoperability is required.


Declare variables and function return types as optional with ? where a nil value is acceptable.

Use implicitly unwrapped types declared with ! only for instance variables that you know will be initialized later before use, such as subviews that will be set up in viewDidLoad(). Prefer optional binding to implicitly unwrapped optionals in most other cases.

When accessing an optional value, use optional chaining if the value is only accessed once or if there are many optionals in the chain:


Use optional binding when it's more convenient to unwrap once and perform multiple operations:

if let textContainer = textContainer {
  // do many things with textContainer

When naming optional variables and properties, avoid naming them like optionalString or maybeView since their optional-ness is already in the type declaration.

For optional binding, shadow the original name whenever possible rather than using names like unwrappedView or actualLabel.


var subview: UIView?
var volume: Double?

// later on...
if let subview = subview, let volume = volume {
  // do something with unwrapped subview and volume

// another example
resource.request().onComplete { [weak self] response in
  guard let self = self else { return }
  let model = self.updateModel(response)

Not Preferred:

var optionalSubview: UIView?
var volume: Double?

if let unwrappedSubview = optionalSubview {
  if let realVolume = volume {
    // do something with unwrappedSubview and realVolume

// another example
UIView.animate(withDuration: 2.0) { [weak self] in
  guard let strongSelf = self else { return }
  strongSelf.alpha = 1.0

Lazy Initialization

Consider using lazy initialization for finer grained control over object lifetime. This is especially true for UIViewController that loads views lazily. You can either use a closure that is immediately called { }() or call a private factory method. Example:

lazy var locationManager = makeLocationManager()

private func makeLocationManager() -> CLLocationManager {
  let manager = CLLocationManager()
  manager.desiredAccuracy = kCLLocationAccuracyBest
  manager.delegate = self
  return manager


  • [unowned self] is not required here. A retain cycle is not created.
  • Location manager has a side-effect for popping up UI to ask the user for permission so fine grain control makes sense here.

Type Inference

Prefer compact code and let the compiler infer the type for constants or variables of single instances. Type inference is also appropriate for small, non-empty arrays and dictionaries. When required, specify the specific type such as CGFloat or Int16.


let message = "Click the button"
let currentBounds = computeViewBounds()
var names = ["Mic", "Sam", "Christine"]
let maximumWidth: CGFloat = 106.5

Not Preferred:

let message: String = "Click the button"
let currentBounds: CGRect = computeViewBounds()
var names = [String]()

Type Annotation for Empty Arrays and Dictionaries

For empty arrays and dictionaries, use type annotation. (For an array or dictionary assigned to a large, multi-line literal, use type annotation.)


var names: [String] = []
var lookup: [String: Int] = [:]

Not Preferred:

var names = [String]()
var lookup = [String: Int]()

NOTE: Following this guideline means picking descriptive names is even more important than before.

Syntactic Sugar

Prefer the shortcut versions of type declarations over the full generics syntax.


var deviceModels: [String]
var employees: [Int: String]
var faxNumber: Int?

Not Preferred:

var deviceModels: Array<String>
var employees: Dictionary<Int, String>
var faxNumber: Optional<Int>

Functions vs Methods

Free functions, which aren't attached to a class or type, should be used sparingly. When possible, prefer to use a method instead of a free function. This aids in readability and discoverability.

Free functions are most appropriate when they aren't associated with any particular type or instance.


let sorted = items.mergeSorted()  // easily discoverable
rocket.launch()  // acts on the model

Not Preferred

let sorted = mergeSort(items)  // hard to discover

Free Function Exceptions

let tuples = zip(a, b)  // feels natural as a free function (symmetry)
let value = max(x, y, z)  // another free function that feels natural

Memory Management

Code (even non-production, tutorial demo code) should not create reference cycles. Analyze your object graph and prevent strong cycles with weak and unowned references. Alternatively, use value types (struct, enum) to prevent cycles altogether.

Extending object lifetime

Extend object lifetime using the [weak self] and guard let self = self else { return } idiom. [weak self] is preferred to [unowned self] where it is not immediately obvious that self outlives the closure. Explicitly extending lifetime is preferred to optional chaining.


resource.request().onComplete { [weak self] response in
  guard let self = self else {
  let model = self.updateModel(response)

Not Preferred

// might crash if self is released before response returns
resource.request().onComplete { [unowned self] response in
  let model = self.updateModel(response)

Not Preferred

// deallocate could happen between updating the model and updating UI
resource.request().onComplete { [weak self] response in
  let model = self?.updateModel(response)

Access Control

Full access control annotation in tutorials can distract from the main topic and is not required. Using private and fileprivate appropriately, however, adds clarity and promotes encapsulation. Prefer private to fileprivate; use fileprivate only when the compiler insists.

Only explicitly use open, public, and internal when you require a full access control specification.

Use access control as the leading property specifier. The only things that should come before access control are the static specifier or attributes such as @IBAction, @IBOutlet and @discardableResult.


private let message = "Great Scott!"

class TimeMachine {  
  private dynamic lazy var fluxCapacitor = FluxCapacitor()

Not Preferred:

fileprivate let message = "Great Scott!"

class TimeMachine {  
  lazy dynamic private var fluxCapacitor = FluxCapacitor()

Control Flow

Prefer the for-in style of for loop over the while-condition-increment style.


for _ in 0..<3 {
  print("Hello three times")

for (index, person) in attendeeList.enumerated() {
  print("\(person) is at position #\(index)")

for index in stride(from: 0, to: items.count, by: 2) {

for index in (0...3).reversed() {

Not Preferred:

var i = 0
while i < 3 {
  print("Hello three times")
  i += 1

var i = 0
while i < attendeeList.count {
  let person = attendeeList[i]
  print("\(person) is at position #\(i)")
  i += 1

Ternary Operator

The Ternary operator, ?: , should only be used when it increases clarity or code neatness. A single condition is usually all that should be evaluated. Evaluating multiple conditions is usually more understandable as an if statement or refactored into instance variables. In general, the best use of the ternary operator is during assignment of a variable and deciding which value to use.


let value = 5
result = value != 0 ? x : y

let isHorizontal = true
result = isHorizontal ? x : y

Not Preferred:

result = a > b ? x = c > d ? c : d : y

Golden Path

When coding with conditionals, the left-hand margin of the code should be the "golden" or "happy" path. That is, don't nest if statements. Multiple return statements are OK. The guard statement is built for this.


func computeFFT(context: Context?, inputData: InputData?) throws -> Frequencies {
  guard let context = context else {
    throw FFTError.noContext
  guard let inputData = inputData else {
    throw FFTError.noInputData

  // use context and input to compute the frequencies
  return frequencies

Not Preferred:

func computeFFT(context: Context?, inputData: InputData?) throws -> Frequencies {
  if let context = context {
    if let inputData = inputData {
      // use context and input to compute the frequencies

      return frequencies
    } else {
      throw FFTError.noInputData
  } else {
    throw FFTError.noContext

When multiple optionals are unwrapped either with guard or if let, minimize nesting by using the compound version when possible. In the compound version, place the guard on its own line, then indent each condition on its own line. The else clause is indented to match the guard itself, as shown below. Example:


  let number1 = number1,
  let number2 = number2,
  let number3 = number3 
else {
// do something with numbers

Not Preferred:

if let number1 = number1 {
  if let number2 = number2 {
    if let number3 = number3 {
      // do something with numbers
    } else {
  } else {
} else {

Failing Guards

Guard statements are required to exit in some way. Generally, this should be simple one line statement such as return, throw, break, continue, and fatalError(). Large code blocks should be avoided. If cleanup code is required for multiple exit points, consider using a defer block to avoid cleanup code duplication.


Swift does not require a semicolon after each statement in your code. They are only required if you wish to combine multiple statements on a single line.

Do not write multiple statements on a single line separated with semicolons.


let swift = "not a scripting language"

Not Preferred:

let swift = "not a scripting language";

NOTE: Swift is very different from JavaScript, where omitting semicolons is generally considered unsafe


Parentheses around conditionals are not required and should be omitted.


if name == "Hello" {

Not Preferred:

if (name == "Hello") {

In larger expressions, optional parentheses can sometimes make code read more clearly.


let playerMark = (player == current ? "X" : "O")

Multi-line String Literals

When building a long string literal, you're encouraged to use the multi-line string literal syntax. Open the literal on the same line as the assignment but do not include text on that line. Indent the text block one additional level.


let message = """
  You cannot charge the flux \
  capacitor with a 9V battery.
  You must use a super-charger \
  which costs 10 credits. You currently \
  have \(credits) credits available.

Not Preferred:

let message = """You cannot charge the flux \
  capacitor with a 9V battery.
  You must use a super-charger \
  which costs 10 credits. You currently \
  have \(credits) credits available.

Not Preferred:

let message = "You cannot charge the flux " +
  "capacitor with a 9V battery.\n" +
  "You must use a super-charger " +
  "which costs 10 credits. You currently " +
  "have \(credits) credits available."

No Emoji

Do not use emoji in your projects. For those readers who actually type in their code, it's an unnecessary source of friction. While it may be cute, it doesn't add to the learning and it interrupts the coding flow for these readers.

No #imageLiteral or #colorLiteral

Likewise, do not use Xcode's ability to drag a color or an image into a source statement. These turn into #colorLiteral and #imageLiteral, respectively, and present unpleasant challenges for a reader trying to enter them based on tutorial text. Instead, use UIColor(red:green:blue) and UIImage(imageLiteralResourceName:).

Organization and Bundle Identifier

Where an Xcode project is involved, the organization should be set to Ray Wenderlich and the Bundle Identifier set to com.raywenderlich.TutorialName where TutorialName is the name of the tutorial project.

Xcode Project settings

Copyright Statement

The following copyright statement should be included at the top of every source file:

/// Copyright (c) 2022 Razeware LLC
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to deal
/// in the Software without restriction, including without limitation the rights
/// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
/// copies of the Software, and to permit persons to whom the Software is
/// furnished to do so, subject to the following conditions:
/// The above copyright notice and this permission notice shall be included in
/// all copies or substantial portions of the Software.
/// Notwithstanding the foregoing, you may not use, copy, modify, merge, publish,
/// distribute, sublicense, create a derivative work, and/or sell copies of the
/// Software in any work that is designed, intended, or marketed for pedagogical or
/// instructional purposes related to programming, coding, application development,
/// or information technology.  Permission for such use, copying, modification,
/// merger, publication, distribution, sublicensing, creation of derivative works,
/// or sale is expressly withheld.
/// This project and source code may use libraries or frameworks that are
/// released under various Open-Source licenses. Use of those libraries and
/// frameworks are governed by their own individual licenses.

Smiley Face

Smiley faces are a very prominent style feature of the raywenderlich.com site! It is very important to have the correct smile signifying the immense amount of happiness and excitement for the coding topic. The closing square bracket ] is used because it represents the largest smile able to be captured using ASCII art. A closing parenthesis ) creates a half-hearted smile, and thus is not preferred.



Not Preferred:




Download Details:

Author: raywenderlich
Source code: https://github.com/raywenderlich/swift-style-guide

License: View license