[英]iOS Animate height constraint issue
self.heightConstraint?.constant = 0.0
self.myLabel.alpha = 0.0
UIView.animate(withDuration: 3.0, animations: {
self.layoutIfNeeded()
})
應該是這樣
為了動畫化約束更改,您需要編寫如下代碼才能工作。
self.heightConstraint?.constant = 0.0
self.myLabel.alpha = 0.0
UIView.animate(withDuration: 5) {
self.layoutIfNeeded()
}
您需要在更新約束常量之前和之后調用self.layoutIfNeeded()
。 將您的代碼更改為:
self.layoutIfNeeded()
UIView.animate(withDuration: 3.0, animations: {
self.heightConstraint?.constant = 0.0
self.myLabel.alpha = 0.0
self.layoutIfNeeded()
})
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