Themes

Story

Ever want to support Night mode? Or skin the app differently depending on the seasons? Or toggle features according to paid status? Well, those are actually reactions to app events.

Many other frameworks encourage you to use hard coded values, like label.xyz_textColors = [.red, .blue], textField.xyz_fonts = [font1, font2], .... This also makes it very hard to change because the usage of index, you need to remember that the 1st index is this theme, the 2nd index is that theme, ... Also, xyz_textColors is like trying to replicate the entire UIKit APIs, which updates often 😱

Themes is here to help. Usually, you have a finite number of colors and fonts in an app. You can have many more but that is not encourage and has design smells. When you have a theme, changing happens in one place.

Features

Usage

Step 1: Create a theme

Declare your theme by conforming to Theme, which is just a marker protocol. You can declare whatever you like, including nested objects, all depending on your need. You can also create as many themes as you like

struct MyTheme: Theme {
  let topImage: UIImage
  let cellColor: UIColor
  let backgroundColor: UIColor
  let name: String
  let titleFont: UIFont
  let subtitleFont: UIFont
}

Then create some themes based on your templates

let dayTheme = MyTheme(topImage: UIImage(named: "day"), cellColor: .white)
let nightTheme = MyTheme(topImage: UIImage(named: "night"), cellColor: .black)

The beauty of this is that you can init your theme from json, which can be fetched from backend 🚀

let json = [
  "primary_color": "#21ABE9",
  "font_name": "Chewy"
]
let unicornTheme = MyTheme(json)

Step 2: Register your current theme

When app launches, you need to declare 1 theme as the current, it can be loaded from cache

ThemeManager.shared.currentTheme = dayTheme

Step 3: React to theme change

You can do this wherever you like. It is set using the current theme, and whenever theme changes

// ViewController.swift
override func viewDidLoad() {
  super.viewDidLoad()

  use(MyTheme.self) {
    $0.title = $1.name
    $0.tableView.backgroundColor = $1.backgroundColor
    $0.navigationController?.navigationBar.setBackgroundImage($1.topImage, for: .default)
    $0.tableView.rowHeight = $1.name == "Unicorn" ? 180 : 120
    $0.tableView.reloadData()
  }
}

// Cell.swift
override func awakeFromNib() {
  super.awakeFromNib()

  imageView.layer.cornerRadius = 5
  imageView.layer.masksToBounds = true

  use(MyTheme.self) {
    $0.titleLabel.font = $1.titleFont
    $0.subtitleLabel.font = $1.subtitleFont
    $0.container.backgroundColor = $1.cellColor
  }
}

Step 4: Change the theme

Change the current theme is as easy as assigning a new theme. All happens in real time and very fast

ThemeManager.shared.currentTheme = nightTheme

Installation

Themes is available through CocoaPods. To install it, simply add the following line to your Podfile:

pod 'Themes'

Themes is also available through Carthage. To install just write into your Cartfile:

github "onmyway133/Themes"

Themes can also be installed manually. Just download and drop Sources folders in your project.

Author

Khoa Pham, onmyway133@gmail.com

Contributing

We would love you to contribute to Themes, check the CONTRIBUTING file for more info.

License

Themes is available under the MIT license. See the LICENSE file for more info.

sangtn/EasyTheme