ios - didMoveToParentViewController 调用了两次

Question

我做了一个简单的测试来了解更多关于包含 View Controller 的信息。
我有一个 View Controller ，我在其中使用两个按钮的操作添加/删除了一个 View Controller :

- (IBAction)myInfoAddAction:(id)sender {
    profileViewController = [[ProfileViewController alloc] init];
    [self addChildViewController: profileViewController];
    UIView *__view = profileViewController.view;
    [self.view addSubview: __view];
    [profileViewController didMoveToParentViewController: self];
}

- (IBAction)myInfoRemoveAction:(id)sender {
    [profileViewController willMoveToParentViewController: nil];
    [profileViewController.view removeFromSuperview];
    [profileViewController removeFromParentViewController];
}

类 ProfileViewController 扩展 UIViewController 并覆盖 willMoveToParentViewController 和 didMoveToParentViewController 方法

-( void)willMoveToParentViewController:(UIViewController *)parent
{
    [super willMoveToParentViewController: parent];
    NSLog(@"willMoveToParentViewController -> %@", self);
}

-( void) didMoveToParentViewController:(UIViewController *)parent
{
    [super didMoveToParentViewController: parent];
    NSLog(@"didMoveToParentViewController -> %@", self);
}

-( void)viewWillAppear:(BOOL)animated
{
    NSLog(@"viewWillAppear -> %@", self);
}

-( void)viewDidDisappear:(BOOL)animated
{
    NSLog(@"viewDidDisappear -> %@", self);
}

当我添加 View Controller 时，我得到了以下日志:

willMoveToParentViewController -> <ProfileViewController: 0x8c52ea0>
viewWillAppear -> <ProfileViewController: 0x8c52ea0>
didMoveToParentViewController -> <ProfileViewController: 0x8c52ea0>
didMoveToParentViewController -> <ProfileViewController: 0x8c52ea0>

当我删除 View Controller 时:

willMoveToParentViewController -> <ProfileViewController: 0x8c52ea0>
didMoveToParentViewController -> <ProfileViewController: 0x8c52ea0>
viewDidDisappear -> <ProfileViewController: 0x8c52ea0>
didMoveToParentViewController -> <ProfileViewController: 0x8c52ea0>

我想知道为什么 didMoveToParentViewController 被调用了两次？

谢谢!

Answer 1

我也遇到了同样的问题。此外，我发现当我在 viewDidLoad 期间添加 subview Controller 时，我只有一条消息。我通过删除对 [super didMoveToParentViewController:] 的调用来修复它。我认为问题与在按钮回调中添加 subview Controller 有关，但我不确定为什么这会导致问题。