iOS之 Auto Layout
1. 动画
// 修改从 StoryBoard 绑定到类的约束的值 self.boxView.constant += 80 // 在动画闭包里对其父级进行 layoutIfNeeded() UIView.animateWithDuration(0.5, animations: { () -> Void in self.view.layoutIfNeeded() })
2. frame的确定
viewDidLoad viewWillAppear viewWillLayoutSubviews viewDidLayoutSubviews // frame 确定 viewDidAppear viewWillDisappear viewDidDisappear
3. why?