Ios 何时以及如何取消子UIViewController

我正在使用以下代码将子视图控制器添加到主视图控制器：

HPSPhotoLibraryOverlayController* controller = [[HPSPhotoLibraryOverlayController alloc] init];

[self.view addSubview:controller.view];

[self addChildViewController:controller];
[controller didMoveToParentViewController:self]; 

子视图控制器控制的视图包含一个按钮，点击该按钮时，应将子视图和子视图控制器从主视图控制器中删除

按下按钮时运行的子视图控制器中的方法如下所示：

-(void)photoLibraryCloseButtonTapped:(id)sender
{
   [self.view removeFromSuperview];

   [(HPSFormController*)_parentController photoLibraryRequestingClose];
}

-(void)photoLibraryRequestingClose
{
    UIViewController* controllerToRemove;
    for (UIViewController* controller in self.childViewControllers) {
        if ([controller isKindOfClass:[HPSPhotoLibraryOverlayController class]])
        {
            [controller removeFromParentViewController];
            controllerToRemove = controller;
        }

    }

    if (controllerToRemove)
    {
        controllerToRemove = nil;
    }

}

然后，主视图控制器中关闭子视图控制器的方法如下所示：

-(void)photoLibraryCloseButtonTapped:(id)sender
{
   [self.view removeFromSuperview];

   [(HPSFormController*)_parentController photoLibraryRequestingClose];
}

-(void)photoLibraryRequestingClose
{
    UIViewController* controllerToRemove;
    for (UIViewController* controller in self.childViewControllers) {
        if ([controller isKindOfClass:[HPSPhotoLibraryOverlayController class]])
        {
            [controller removeFromParentViewController];
            controllerToRemove = controller;
        }

    }

    if (controllerToRemove)
    {
        controllerToRemove = nil;
    }

}

这段代码可以正常工作。然而，在我看来，当子视图控制器的-（void）photoLibraryCloseButtonTapped:（id）sender方法仍在运行时（即-（void），子视图控制器似乎被设置为nilphotoLibraryRequestingClose方法尚未返回，但我正在取消调用photoLibraryRequestingClose的子视图控制器

我正在使用ARC

为什么会这样做？我应该以不同的方式管理子视图控制器的移除，记住触发移除子控制器的按钮是由子视图控制器管理的

---

非常感谢。

请查看Apple View Controller编程指南，特别是清单14-2：

- (void) hideContentController: (UIViewController*) content
{
   [content willMoveToParentViewController:nil];
   [content.view removeFromSuperview];
   [content removeFromParentViewController];
}

回答您的问题时，您应该如下更改代码：

- (void)photoLibraryCloseButtonTapped:(id)sender
{
   [(HPSFormController*)_parentController photoLibraryControllerRequestingClose:self];
}

- (void)photoLibraryControllerRequestingClose:(UIViewController *)childController
{
   [childController willMoveToParentViewController:nil];
   [childController.view removeFromSuperview];
   [childController removeFromParentViewController];
}

---

请查看Apple View Controller编程指南，特别是清单14-2：

- (void) hideContentController: (UIViewController*) content
{
   [content willMoveToParentViewController:nil];
   [content.view removeFromSuperview];
   [content removeFromParentViewController];
}

回答您的问题时，您应该如下更改代码：

- (void)photoLibraryCloseButtonTapped:(id)sender
{
   [(HPSFormController*)_parentController photoLibraryControllerRequestingClose:self];
}

- (void)photoLibraryControllerRequestingClose:(UIViewController *)childController
{
   [childController willMoveToParentViewController:nil];
   [childController.view removeFromSuperview];
   [childController removeFromParentViewController];
}