使用 Swift 动画视图高度 [英] Animate view height with Swift

问题描述

我的 ViewController 中有视图 sView.它的高度有约束 - 我为这个约束创建了 IBOutlet - sViewHeightConstraint.我想用动画降低 sView 的高度.

I have view sView inside my ViewController. It height has constraint - I created IBOutlet for this constraint - sViewHeightConstraint. I want to decrease height of sView with animation.

我创建了函数

UIView.animateWithDuration(5.5, animations: {
                self.sViewHeightConstraint.constant = 50
            })

视图高度正在改变，但我没有看到任何动画.我做错了什么?

Height of view is changing but i don't see any animation. What I am doing wrong?

推荐答案

使用 layoutIfNeeded()

 view.layoutIfNeeded() // force any pending operations to finish

 UIView.animateWithDuration(0.2, animations: { () -> Void in
    self.sViewHeightConstraint.constant = 50
    self.view.layoutIfNeeded()
})

斯威夫特 3

view.layoutIfNeeded() 
sViewHeightConstraint.constant = 50

UIView.animate(withDuration: 1.0, animations: { 
     self.view.layoutIfNeeded() 
})

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