Swift iOS14 动画约束

Question

我正在尝试为视图的底部约束设置动画，使其向上滑动。

这就是我正在做的，但它只是立即跳到新位置，它不会滑动：

UIView.animate(withDuration: 0.4) {
    self.pickerBottomConstraint.constant += 300
    self.agePicker.setNeedsLayout()
    self.agePicker.layoutIfNeeded()
}

有谁知道如何在 iOS14 中设置动画约束？

Answer 1

你需要

self.pickerBottomConstraint.constant += 300 // this should be outside of animate
UIView.animate(withDuration: 0.4) { 
   self.view.layoutIfNeeded()  // this should be called for at least the direct parent of the animated picker 
}