What/How to triggers the close-iris animation of UIImagePickerController?

I'm using a custom overlay view and showsCameraControls = NO. When I'm done I dismissModalViewCont开发者_JS百科rollerAnimated:YES. What appears to happen is that the iris appears fully closed (ie. no closing animation - just poof and it's closed) and then immediately slides down off the screen.

As a test I manually called viewWillDisappear on the UIImagePickerController and that makes the closed iris appear, but again no smooth animation.

I also tried wrapping the dismiss in a long animation transaction and that just made the re-appearence of the underlying navigation toolbar slow down. The iris behaved just as above.

I don't want to have to make my own iris animation - that would be uncool!

PS: Using sdk 4.0

To partially answer my own question, the best I have been able to come up with so far is:

- (void)imagePickerController:(UIImagePickerController*)picker 
didFinishPickingMediaWithInfo:(NSDictionary*)info
{
    [picker viewWillDisappear:YES];

    [self performSelector:@selector(processPickerImage:) 
               withObject:[[info objectForKey:UIImagePickerControllerOriginalImage] retain] 
               afterDelay:0.1];
}

-(void) processPickerImage:(UIImage *)uiImage
{

    // do stuff
    [self dismissModalViewControllerAnimated:YES];
    // dismiss your custom overlay etc.
    [uiImage release];
}

It doesn't actually animate the iris, but at least it is onscreen immediately so the user recognises that the photo taking is done. I'm also not super happy that viewWillDisappear gets called twice on the UIImagePickerController - I'm not sure it's guaranteed to be safe.

Also the status bar appears over the iris which is annoying.

I'm hoping someone else has a better solution?