调用popToRootViewControllerAnimated时未调用viewWillDisappear [英] viewWillDisappear not called when calling popToRootViewControllerAnimated
问题描述
我在旧版应用程序上工作，发现我的view[Will/Did]Disappear方法并非总是能正确触发.
I work on a legacy application, and have found out, that my view[Will/Did]Disappear methods are not always fired properly.
情况是，我在AppDelegate中将一个(自定义)UIViewController设置为rootViewController.这个rootViewController有一个UINavigationController，上面有两个视图控制器.当用户按下主页按钮时，该用户将注销.当他稍后返回应用程序时，该应用程序调用[UINavigationController popToRootViewControllerAnimated:YES]，然后显示模式UIViewController进行登录.
The case is, I have a (custom) UIViewController set as rootViewController in AppDelegate. This rootViewController has a UINavigationController, which has two view controllers pushed on it. When the user presses the home button, the user is logged out. When he later returns to the app, the application calls [UINavigationController popToRootViewControllerAnimated:YES] and then displays a modal UIViewController for logging in.
问题是:当我正常地在UINavigationController上推入/弹出时，我的viewWillDisappear方法会被正确调用.但是当我使用popToRootViewControllerAnimated:方法时，在弹出的所有viewController上都不会调用viewWillDisappear.
The problem is: When I push/pop on the UINavigationController normally, my viewWillDisappear method is called properly. But when I use the popToRootViewControllerAnimated: method, viewWillDisappear is not called on any of the viewControllers that are popped off.
在Internet上搜索仅给出两个可能的原因:
Searching on the internet has only given two possible reasons:
这些建议在我的应用程序中都不存在.而且我不知道在哪里看.有人对应用程序做错了什么建议吗?
None of these suggestions are the case in my app. And I have no idea where to look. Anybody has a suggestion to what has been done wrong in the app?
推荐答案
该视图可能不在屏幕上.必须在屏幕上(可见)调用viewWillDisappear:方法.如果它是从后台回来的，则看不到.
The view probably wasn't onscreen. It has to be onscreen (visible) for the viewWillDisappear: method to be called. If it's coming back from the background, it wasn't visible.
您可以尝试使用willMoveToParentViewController:，当视图控制器从其父级中移除时会调用它.
You could try using willMoveToParentViewController: which is called when the view controller is removed from its parent.
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