swift游乐场中的动画问题

Question

我对 swift 动画完全不熟悉，我通过使用 Playground 开始了这个概念，下面是我的代码，我不知道为什么它不起作用。

import UIKit
import PlaygroundSupport

let liveViewFrame = CGRect(x: 0, y: 0, width: 500, height: 500)
let liveView = UIView(frame: liveViewFrame)
liveView.backgroundColor = .white
PlaygroundPage.current.liveView = liveView

let smallFrame = CGRect(x: 0, y: 0, width: 100, height: 100)
let square = UIView(frame: smallFrame)
square.backgroundColor = .purple
liveView.addSubview(square)

UIView.animate(withDuration: 3.0) {
    liveView.backgroundColor = .blue
}

Answer 1

这段代码运行良好