ios - 为什么在使用手动 View 包含时在错误的时间调用 viewWillDisappear？

Question

这就是我使用 containment API 的方式。根据docs是正确的。

[self.childViewController willMoveToParentViewController:nil];
[UIView animateWithDuration:0.25 animations:^{
    self.childViewController.view.frame = ... // View Animation
} completion:^(BOOL finished) {
    [self.childViewController.view removeFromSuperview]; // triggers `viewWillDisappear`
    [self.childViewController removeFromParentViewController];
}];

我希望 viewWillDisappear 在动画开始之前被调用，viewDidDisappear 在动画完成之后被调用。然而，在动画完成后，它们都会被快速连续地调用。

将 [self.childViewController.view removeFromSuperview]; 移动到动画 block 修复了这个问题，但代码看起来不对:

[self.childViewController willMoveToParentViewController:nil];
[UIView animateWithDuration:0.25 animations:^{
    self.childViewController.view.frame = ... // View Animation
    [self.childViewController.view removeFromSuperview]; // triggers `viewWillDisappear`
} completion:^(BOOL finished) {
    [self.childViewController removeFromParentViewController];
}];

有谁知道在正确的时间调用 viewWillDisappear 的正确方法是什么？

Answer 1

答案是使用 – beginAppearanceTransition:animated: & endAppearanceTransition

If you are implementing a custom container controller, use this method to tell the child that its views are about to appear or disappear. Do not invoke viewWillAppear:, viewWillDisappear:, viewDidAppear:, or viewDidDisappear: directly.

修改后的代码:

[self.childViewController willMoveToParentViewController:nil];
[self.childViewController beginAppearanceTransition:NO animated:YES];
[UIView animateWithDuration:0.25 animations:^{
    self.childViewController.view.frame = ... 
} completion:^(BOOL finished) {
    [self.childViewController.view removeFromSuperview]; 
    [self.childViewController removeFromParentViewController];
    [self.childViewController endAppearanceTransition];
}];