View Controller Containment如何在iOS 5中运行？ [英] How does View Controller Containment work in iOS 5?

问题描述

在WWDC 2011 Session 102中，Apple推出了View Controller Containment，它能够创建自定义视图控制器容器，类似于 UITabBarController ， UINavigationController 等等。

In WWDC 2011 Session 102, Apple introduced View Controller Containment, which is the ability to create custom view controller containers, analogous to UITabBarController, UINavigationController, and the like.

我多次观看这些例子。有一系列与这种模式相关的方法，但要确切地弄清楚它们有点困难。我将在这里发布我认为正在发生的事情，看看社区是否会确认或否定我的怀疑。

I watched the examples several times. There are a flurry of methods associated with this pattern, but it was a little hard to figure them out exactly. I'm going to post here what I think is going on and see if the community will confirm or disconfirm my suspicions.

场景1：从没有父母移动到新的父视图控制器

[vc willMoveToParentViewController:self];
[self addChildViewController:vc];
[self.view addSubview:vc.view]; // or something like this.
[vc didMoveToParentViewController:self];

前两行必须按照给定的顺序发生，还是可以反转？

Do the first two lines have to occur in the order given, or can they be reversed?

场景2：从父视图控制器移动到无父视图控制器

[vc willMoveToParentViewController:nil];
[vc.view removeFromSuperview];
[vc removeFromParentViewController];

是否还需要调用 [vc didMoveToParentViewController：nil] ？会话102 中的示例在这种情况下没有这样做，但我不知道这是否是遗漏。

Is it also necessary to call [vc didMoveToParentViewController:nil]? The examples in Session 102 did not do this in this scenario, but I don't know whether that was an omission or not.

场景3：从一个父视图控制器移动到另一个父视图控制器

这可能会以下列方式发生，因为每个父视图控制器中的逻辑将封装。

This will likely occur in the following way, because the logic in each parent view controller will be encapsulated.

// In the old parent
[vc willMoveToParentViewController:nil];
[vc.view removeFromSuperview];
[vc removeFromParentViewController];

// In the new parent
[vc willMoveToParentViewController:self];
[self addChildViewController:vc];
[self.view addSubview:vc.view];
[vc didMoveToParentViewController:self];

问题

我的主要问题是：一般来说，视图控制器包含应该如何工作？上面给出的机制是否正确？

My main question is this: Is this how view controller containment should work, in general? Are the mechanics given above correct?

在调用 addChildViewController之前，是否需要调用 willMoveToParentViewController ？这对我来说似乎是合乎逻辑的顺序，但这是非常必要的吗？

Is it necessary to call willMoveToParentViewController before calling addChildViewController? This seems like the logical order to me, but is it strictly necessary?

是否需要调用 didMoveToParentViewController：nil 调用 removeFromParentViewController ？

推荐答案

UIViewController docs非常清楚何时何何不调用 willMove / didMove 方法。查看实现容器视图控制器文档。

The UIViewController docs are pretty clear on when and when not to call willMove/didMove methods. Check out the "Implementing a Container View Controller" documentation.

文档说，如果你不覆盖 addChildViewController ，你不必调用 willMoveToParentViewController：方法。但是，您需要在转换完成后调用 didMoveToParentViewController：方法。 同样，在调用 removeFromParentViewController 方法之前，容器视图控制器负责调用 willMoveToParentViewController：方法。 。code> removeFromParentViewController 方法调用子视图控制器的 didMoveToParentViewController：方法。

The docs say, that if you do not override addChildViewController, you do not have to call willMoveToParentViewController: method. However you do need to call the didMoveToParentViewController: method after the transition is complete. "Likewise, it is is the responsibility of the container view controller to call the willMoveToParentViewController: method before calling the removeFromParentViewController method. The removeFromParentViewController method calls the didMoveToParentViewController: method of the child view controller."

此外，还有一个例子可以解决这里和示例代码此处。

Also, there is an example worked out here and sample code here.

祝你好运

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