[super viewWillAppear]做什么，什么时候需要它？ [英] What does [super viewWillAppear] do, and when is it required?

问题描述

-(void)viewWillAppear:(BOOL)animated{
//something here
[super viewWillAppear];
}

是 [super viewWillAppear]; 总是需要？

推荐答案

首先，正确的锅板应该是：

First of all, the correct boiler plate should be:

-(void)viewWillAppear:(BOOL)animated{
   [super viewWillAppear:animated];
   //something here
}

换句话说，调用 super ，然后自己做。您必须将动画参数传递给 super 。

In other words, call super first, then do your own thing. And you have to pass the animated parameter to super.

你通常想在任何方法中调用超类的实现。在许多语言中它是必需的。在Objective-C它不是，但你可以很容易遇到麻烦，如果你不把它放在你的方法的顶部。

You usually want to call the super class' implementation first in any method. In many languages it's required. In Objective-C it's not, but you can easily run into trouble if you don't put it at the top of your method. (That said, I sometimes break this pattern.)

正在调用 super's 实现必需？在这种特定方法的情况下，如果你不调用它，你可能会得到意想不到的行为（例如，如果你已经子类化一个 UINavigationController ）。所以答案是没有不是在技术意义上，但你应该总是这样做。

Is calling super's implementation required? In the case of this particular method you could get unexpected behavior if you don't call it (especially if you have subclassed a UINavigationController for example). So the answer is no not in a technical sense, but you should probably always do it.

然而，在许多其他方法可能没有调用 super 的好理由。

However, in many other methods there may be good reasons for not calling super.

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