Swift ThenSwift 初始化语法糖-技术圈

Then 是实现 Swift 对象初始化的一个语法糖

初始化 UILabel 并设置其属性



let label = UILabel().then {

  $0.textAlignment = .center

  $0.textColor = .black

  $0.text = "Hello, World!"

}

相当于：



let label: UILabel = {

  let label = UILabel()

  label.textAlignment = .center

  label.textColor = .black

  label.text = "Hello, World!"

  return label

}()

技巧

在所有的 NSObject 子类中使用 then()



let queue = OperationQueue().then {

  $0.maxConcurrentOperationCount = 1

}

在自定义类中使用，只需进行简单扩展：



extension MyType: Then {}



let instance = MyType().then {

  $0.really = "awesome!"

}

拷贝值类型数据时候 with()



let newFrame = oldFrame.with {

  $0.size.width = 200

  $0.size.height = 100

}

newFrame.width // 200

newFrame.height // 100

使用 do() 减少类型处理



UserDefaults.standard.do {

  $0.set("devxoul", forKey: "username")

  $0.set("devxoul@gmail.com", forKey: "email")

  $0.synchronize()

}

真实示例：



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)

  }



}

安装

For iOS 8+ projects with CocoaPods:
```
pod 'Then'
```

For iOS 8+ projects with Carthage:
```
github "devxoul/Then"
```

Using Swift Package Manager:



import PackageDescription



let package = Package(

  name: "MyAwesomeApp",

  dependencies: [

    .Package(url: "https://github.com/devxoul/Then", majorVersion: 2),

  ]

)