UIViewController:调用viewWillAppear，不调用viewDidAppear [英] UIViewController: viewWillAppear is called, viewDidAppear not

问题描述

在UIViewController子类中，我具有以下方法:

In a UIViewController subclass, I have the following methods:

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    // do something
    myTextField.text = @"Default";
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    // do something
    [myTextField selectAll:self];
    [myTextField becomeFirstResponder];
}

- (void)viewDidLoad {
    [super viewDidLoad];    
    // do something
    myTextField.delegate = self;
}

NIB是使用Interface Builder创建的.导航控制器通过pushViewController推送相应的视图控制器对象.

The NIB has been created using Interface Builder. The corresponding view controller object is pushed by the navigation controller through pushViewController.

实际行为是在文本字段中显示默认文本条目，选择整个文本并将该文本字段设置为第一响应者.

The inteded behavior is to show a default text entry in a text field, to select the entire text and to set the text field as first responder.

但是，虽然调用了viewDidLoad和viewWillAppear方法，但没有调用viewDidAppear方法.有人可以告诉我为什么吗?我在网络上发现的大多数问题都在这里处理，而viewWillAppear/viewDidAppear都无法正常工作.我还理解，在子视图或以编程方式创建的视图中，不会使用这些方法.但这在万一情况下不适用，我也想知道为什么要使用其中一种生命周期"方法，而另一种则不行.

However, while methods viewDidLoad and viewWillAppear are called, the method viewDidAppear is not called. Can anybody tell me why? Most questions I found on the web and here deal with both viewWillAppear/viewDidAppear are not working; I also understood that in subviews or programmatically created views these methods are not evoked; but this does not apply in case and also I wonder why one of these "lifecycle" methods is evoked and the other not.

有什么主意吗?谢谢！

推荐答案

我遇到了这个问题:viewWillAppear被调用，但viewDidAppear没有！

I had this issue happen to me: viewWillAppear was being called but viewDidAppear was not!

我终于发现这是因为我有一个tabBarController，其中我自己重载了viewDidAppear而忘记了[super viewDidAppear:animated];

I finally figured out that this was because I had a tabBarController where I overloaded it's own viewDidAppear and forgot the [super viewDidAppear:animated];

它在每个选项卡中的每个VC都抛出了！重新添加该行以修复我的其他VC's.

It threw off every VC in every tab! adding that line back in fixed it for my other VC's.

希望这对某人有帮助！

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