帧突然改变而不是动画 [iOS]

Question

我的应用程序中有一个带有滚动视图的视图（百分比计算器）。我正在尝试为视图设置动画以使其飞出，然后按下按钮再次从左侧飞入，尽管内容不同。这是我的代码：

func next()
{
    UIView.animateWithDuration(0.5, animations: {
        self.mainView.frame = CGRectMake(-500, self.view.bounds.height/2-self.mainHeight/2, self.mainWidth, self.mainHeight)
        self.mainView.center.x -= 600
    }) { (success) in
        self.mainView.center.x += 1200    
    }

    UIView.animateWithDuration(0.5, animations: {
        self.mainView.frame = CGRectMake(self.view.bounds.width/2-self.mainWidth/2, self.view.bounds.height/2-self.mainHeight/2, self.mainWidth, self.mainHeight)
    }) { (success) in
        print("Animation Successful!")
        self.drawView()
    }
}

我不明白为什么，但没有出现动画，视图完全消失，我在日志中看到 "Animation Successful"。明确地说，我以编程方式创建了视图。

这是viewDidLoad()中的代码；视图在调用时正确显示：

    mainHeight = self.view.bounds.height * 0.85
    mainWidth = self.view.bounds.width * 0.85
    let viewHeight = self.view.bounds.height
    let viewWidth = self.view.bounds.width

    mainView.frame = CGRectMake(viewWidth/2-mainWidth/2, viewHeight/2-mainHeight/2, mainWidth, mainHeight)
    mainView.layer.cornerRadius = 8
    mainView.layer.masksToBounds = true
    mainView.backgroundColor = getColor(0, green: 179, blue: 164)
    self.view.addSubview(mainView)

    scrollView.frame = CGRectMake(0, 0, mainWidth, mainHeight)
    scrollView.contentSize = CGSizeMake(mainWidth, 800)
    self.mainView.addSubview(scrollView)

    contentView.frame = CGRectMake(0, 0, mainWidth, 800);
    contentView.backgroundColor = getColor(0, green: 179, blue: 164)
    contentView.layer.masksToBounds = true
    contentView.clipsToBounds = true
    self.scrollView.addSubview(contentView)

Answer 1

将 self.layoutViewIfNeeded() 放在 frame/center 更改之前。此外，您可能需要将下一个动画放在下一个动画的完成处理程序中。

func next() {
    UIView.animateWithDuration(0.5, animations: {
        self.view.layoutIfNeeded() // add this
        self.mainView.frame = CGRectMake(-500, self.view.bounds.height/2-self.mainHeight/2, self.mainWidth, self.mainHeight)
        self.mainView.center.x -= 600

    }) { (success) in
        self.view.layoutIfNeeded() // add this
        self.mainView.center.x += 1200

        // your next animation within a completion handler of previous animation
        UIView.animateWithDuration(0.5, animations: {

            self.mainView.frame = CGRectMake(self.view.bounds.width/2-self.mainWidth/2, self.view.bounds.height/2-self.mainHeight/2, self.mainWidth, self.mainHeight)

        }) { (success) in

            print("Animation Successful!")
            self.drawView()
        }
    }
}

我还没有测试过，也许需要一些更改或行排序。

Answer 2

在 Swift 3 中，我必须设置框架，然后然后调用 layoutIfNeeded().

例如，动画 spring:

UIView.animate(withDuration: 0.3, delay: 0.1, usingSpringWithDamping: 0.7, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
        self.subView.frame = CGRect(x: 0, y: 0, width: 500, height: 200)
        self.view.layoutIfNeeded()
    }) { (_) in
        // Follow up animations...
    }

帧突然改变而不是动画 [iOS]

Frames changing suddenly instead of animating [iOS]

animation

uiview

uianimation

ios

swift