在iOS中逐步添加矩形动画

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建矩形图层
        let rectLayer = CALayer()
        rectLayer.frame = CGRect(x: 50, y: 50, width: 100, height: 100)
        rectLayer.backgroundColor = UIColor.red.cgColor
        
        // 添加矩形图层到视图
        view.layer.addSublayer(rectLayer)
        
        // 创建动画对象
        let animation = CAKeyframeAnimation(keyPath: "position")
        
        // 设置动画路径
        let path = UIBezierPath()
        path.move(to: CGPoint(x: 50, y: 50))
        path.addLine(to: CGPoint(x: 200, y: 50))
        path.addLine(to: CGPoint(x: 200, y: 200))
        path.addLine(to: CGPoint(x: 50, y: 200))
        path.addLine(to: CGPoint(x: 50, y: 50))
        animation.path = path.cgPath
        
        // 设置动画持续时间
        animation.duration = 5.0
        
        // 设置动画重复次数
        animation.repeatCount = Float.infinity
        
        // 将动画添加到图层
        rectLayer.add(animation, forKey: "rectAnimation")
    }
}