Then

October 23, 2020

> 本文由 [简悦 SimpRead](http://ksria.com/simpread/) 转码，原文地址 [github.com](https://github.com/devxoul/Then)

✨ Super sweet syntactic sugar for Swift initializers.

At a Glance

Initialize UILabel then set its properties.

let label = UILabel().then {
  $0.textAlignment = .center
  $0.textColor = .black
  $0.text = "Hello, World!"
}

This is equivalent to:

let label: UILabel = {
  let label = UILabel()
  label.textAlignment = .center
  label.textColor = .black
  label.text = "Hello, World!"
  return label
}()

Tips and Tricks

You can use then() to all of NSObject subclasses.

let queue = OperationQueue().then {
  $0.maxConcurrentOperationCount = 1
}

Want to use with your own types? Just make extensions.

extension MyType: Then {}

let instance = MyType().then {
  $0.really = "awesome!"
}

Use with() when copying the value types.

let newFrame = oldFrame.with {
  $0.size.width = 200
  $0.size.height = 100
}
newFrame.width // 200
newFrame.height // 100

Use do() to do something with less typing.

UserDefaults.standard.do {
  $0.set("devxoul", forKey: "username")
  $0.set("devxoul@gmail.com", forKey: "email")
  $0.synchronize()
}

Real World Example

Here's an example usage in an UIViewController subclass.

final class MyViewController: UIViewController {

  let titleLabel = UILabel().then {
    $0.textColor = .black
    $0.textAlignment = .center
  }

  let tableView = UITableView().then {
    $0.backgroundColor = .clear
    $0.separatorStyle = .none
    $0.register(MyCell.self, forCellReuseIdentifier: "myCell")
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    self.view.addSubview(self.titleLabel)
    self.view.addSubview(self.tableView)
  }

}

Installation

Using CocoaPods:

Using Swift Package Manager:

import PackageDescription

let package = Package(
  name: "MyAwesomeApp",
  dependencies: \[
    .Package(url: "https://github.com/devxoul/Then", majorVersion: 2),
  \]
)

License

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