How to dismiss a modal view as soon as it's displayed (without user interaction)

I apologize if my question may result trivial or obscure. I am using a view presented modally. In order to achieve a little 'scenographic' animation effect, based on the value of a parameter, I wish to reach the following behavior:

If value is 0, the view presented modally stays on display and allows user actions until a back button is pressed (in which case the view is dismissed)

if value is 1, the view is presented modally, then it is开发者_JAVA技巧 dismissed immediately and an alert view appears above the calling view.

Now, I have tried to put the control on the value in the viewDidAppear method, within the modal view controller like this

- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:YES];
if (<value> == 1) {
[self dismissModalViewControllerAnimated:YES];
                  }
}

And what I got is: If value is 0 the modal view stays on as planned

If value is 1 the modal view is dismissed as planned, but the application crashes immediately after. The debugger seems to suggest that the problem arose within

-[UIWindowController transitionViewDidComplete: fromView:toView]

And now the question(s): Am I trying to do something seriously illegal/impossible?

If a solution exists, it consists on just moving the control to another method? If yes, which method?

Or the solutions is far more complex?

Thank you

---

Might be that UIWindowController is mistakenly assuming the view is still visible when the viewDidAppear notification call returns.

Try using performSelector:withObject:afterDelay: with a zero delay - it will call the selected method as soon as possible after control returns to the run loop (and out of the UIWindowController call stack):

- (void) delayedDismissOfModalViewController {
    [self dismissModalViewControllerAnimated:YES];
}

- (void) viewDidAppear: (BOOL) animated {
   [super viewDidAppear:YES];

   if (<value> == 1) {
      [self performSelector: @selector(delayedDismissOfModalViewController)
                 withObject: nil
                 afterDelay: 0];
   }
}