Modal dialog for iOS.

gistfile1.m

- (void)presentModalView
{
    CGFloat bounceDistance = 10.0;
    CGFloat modalWidthPercentage = 0.9;
    CGFloat modalHeightPercentage = 0.8;

    UIWindow *keyWindow = [[UIApplication sharedApplication] keyWindow];
    CGRect frame = keyWindow.bounds;
    
    // The screenView is a plain black view with opacity
    UIView *screenView = [[UIView alloc] initWithFrame:[keyWindow bounds]];
    screenView.backgroundColor = [UIColor blackColor];
    screenView.alpha = 0.0;
    // Adding a modal dialog to the app this way will cause rotation issues,
    // but we should be OK since we do not allow rotation
    [keyWindow addSubview:screenView];
    
    // The modalView sits on top of the screenView
    CGPoint center = keyWindow.center;
    CGRect modalFrame = frame;
    
    // Set the size of our modal dialog
    modalFrame.size.width *= modalWidthPercentage;
    modalFrame.size.height *= modalHeightPercentage;
    modalFrame.origin.x = (frame.size.width - modalFrame.size.width) / 2;
    modalFrame.origin.y = modalFrame.size.height * -1;
    
    UIView *modalView = [[UIView alloc] initWithFrame:modalFrame];
    modalView.backgroundColor = [UIColor whiteColor];
    [keyWindow addSubview:modalView];
    
    [UIView animateWithDuration:0.20 animations:^{
        // Fade the screen in
        screenView.alpha = 0.7;
        // Apply the bounce distance to the Y coordinate
        modalView.center = CGPointMake(center.x, center.y + bounceDistance);
    } completion:^(BOOL finished){
        [UIView animateWithDuration:0.20 animations:^{
            // Move the modal view back to true center
            modalView.center = center;
        } completion:nil];
    }];
}