如何在Swift3中实现可选动画功能

import UIKit

class ViewController: UIViewController {
    
    var animatedView: UIView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建一个UIView对象
        animatedView = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
        animatedView.backgroundColor = UIColor.red
        view.addSubview(animatedView)
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        // 实现可选动画功能
        animateView()
    }
    
    func animateView() {
        // 设置动画的初始状态
        animatedView.alpha = 0.0
        
        // 使用UIView的动画方法实现动画效果
        UIView.animate(withDuration: 1.0, animations: {
            // 设置动画的最终状态
            self.animatedView.alpha = 1.0
        }, completion: nil)
    }
}