viewDidDisappear not called when use presentViewCo

问题:

I have an UIViewController having this method:

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    NSLog(@"DISAPPEAR");
    lastKnownOrientation = [self interfaceOrientation];
}


-(void)openSendVC{
    SendMsgViewController *vc = [[SendMsgViewController alloc]initWithNibName:@"SendMsgViewController" bundle:nil];
    [self.navigationController pushViewController:vc animated:NO];  
}

In the second view controller (SendMsgViewController) viewDidLoad I have the following:

[self presentViewController:picker animated:YES completion:NULL];

where picker is an UIImageViewPicker.

The problem is, when I call the method openSendVC a new controller is opened, but viewWillDisappear (of the first viewController) is not called.

回答1:

That is the correct behavior. Here's an excerpt about viewWillDisappear: from the UIViewController API docs:

This method is called in response to a view being removed from a view hierarchy. This method is called before the view is actually removed and before any animations are configured.

Presenting a new view controller so that it hides the other view controller doesn't count as the view disappearing—only actually being removed from a view hierarchy does (e.g., with something like popViewControllerAnimated:).