先上个图
我们先打开Xcode工程，File->New->Playground或者option+shift+command+N
选择Single View。
然后就能看到熟悉的swift的控制器的相关代码了。
import UIKit
import PlaygroundSupport
class MyViewController : UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
self.view.backgroundColor = UIColor.white
let label = UILabel()
label.frame = CGRect(x: 100, y: 200, width: 200, height: 20)
label.text = "Hello World!"
label.textColor = .black
label.textAlignment = .center
label.backgroundColor = UIColor.cyan
self.view.addSubview(label)
let animate = CABasicAnimation(keyPath: "opacity")
animate.fromValue = 0
animate.toValue = 0.8
animate.duration = 0.75
animate.repeatCount = MAXFLOAT
animate.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
animate.fillMode = kCAFillModeBoth
animate.autoreverses = true
label.layer.add(animate, forKey: "key_opacity")
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()
//let demoView = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
//demoView.backgroundColor = UIColor.brown
//PlaygroundPage.current.liveView = demoView
通过PlaygroundSupport的PlaygroundPage.current.liveView就可以设置当前要显示的View或Controller了。效果如下。
1. 我们要如何看到界面呢？
打开assistant editor即可
2. 我们怎样调试界面呢？
按住左下角的三角按钮，会弹出一个菜单，选择Manually Run就可以手动运行Playground了，以后每次点击三角按钮才会运行Playground。
这是不是很简单呢？
