查看动画不起作用 - ios Swift 3

Question

我有这段代码应该给 mainView 一个弹簧效果。

但我没有得到想要的效果，我只是通过 Storyboards 将 Transition 样式应用于 ViewController。

override func viewDidLoad()
{
    super.viewDidLoad()

    self.statusBarHidden = UIApplication.shared.isStatusBarHidden
    UIApplication.shared.setStatusBarHidden(true, with: .none)


    self.mainView = UIView(frame: CGRect(x: self.view.getWidth/20, y:self.view.getHeight/6, width:self.view.getWidth/1.3 , height: self.view.getHeight/1.3))

    self.mainView.backgroundColor = UIColor.blue
    self.mainView.center.x = self.view.center.x
    self.mainView.center.y = self.view.center.y

    self.mainView.transform = CGAffineTransform(scaleX: 0.8, y: 1.2) // initial view distorted scale so it has a starting point for the animation

    self.view.addSubview(self.mainView)

    UIView.animate(withDuration: 0.3, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0, options: [], animations: {
        self.mainView.transform = .identity // get back to original scale in an animated way
    }, completion: nil)
}  

能否请您帮忙将弹簧效果添加到 mainView 中？

谢谢

Answer 1

要使用动画，您应该了解视图控制器的生命周期。这对于您描述的情况至关重要，因为您应该了解何时以及为何开始动画。

首先请阅读官方documentation的生活圈。

代码，但试着理解为什么它现在可以工作：

  class ViewController: UIViewController {

    var mainView = UIView()

    override func viewDidLoad() {
        super.viewDidLoad()
        addMainView()
    }

    override func viewDidAppear(_ animated: Bool) {
       super.viewDidAppear(animated)
       animateMainView()
    }

    func addMainView() {
        self.mainView = UIView(frame: CGRect(x: self.view.frame.width/20, y:self.view.frame.height/6, width:self.view.frame.width/1.3 , height: self.view.frame.height/1.3))

        self.mainView.backgroundColor = UIColor.blue
        self.mainView.center.x = self.view.center.x
        self.mainView.center.y = self.view.center.y

        self.view.addSubview(self.mainView)
    }

    func animateMainView() {

        self.mainView.transform = CGAffineTransform(scaleX: 0.8, y: 1.2) // initial view distorted scale so it has a starting point for the animation

        UIView.animate(withDuration: 0.9, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0, options: [], animations: {
            self.mainView.transform = .identity // get back to original scale in an animated way
        }, completion: nil)
    }
}

动画示例：