直接上代碼

  override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.white
        // Do any additional setup after loading the view.
        
        tempView = UIView(frame: CGRect(x: 100, y: 200, width: 200, height: 300));
        tempView?.backgroundColor = UIColor.black
        self.view.addSubview(tempView!)

        let animation: CAGradientLayer = CAGradientLayer()
        animation.frame = CGRect(x: 0, y: 0, width: 200, height: 300)
        animation.startPoint = CGPoint(x: 0, y: 0)
        animation.endPoint = CGPoint(x: 0, y: 1)
        let color = UIColor(red: 216.0/255.0, green: 114.0/225.0, blue: 213.0/255.0, alpha: 1.0)
        let color1 = UIColor(red: 61.0/255.0, green: 226.0/225.0, blue: 210.0/255.0, alpha: 1.0)
        animation.colors = [UIColor.clear.cgColor,color1.cgColor, color.cgColor]
        animation.locations = [0.0,0.1,0.2]
        tempView?.layer.addSublayer(animation)
        
        let gradientAnimation: CABasicAnimation = CABasicAnimation()
        gradientAnimation.keyPath = "locations"
        gradientAnimation.fromValue = [0.0,0.1,0.2]
        gradientAnimation.toValue = [0.5,0.9,1.0]
        gradientAnimation.duration = 3.0
        gradientAnimation.repeatCount = 9;
        animation.add(gradientAnimation, forKey: nil);
}

效果圖如下

469A2AE5-4F7E-4A25-B3C2-A3CE0ADE19C1.GIF