UIView动画

- (void) fadeOut: (id) sender
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration:1.0];
    [[self.view viewWithTag:999] setAlpha:0.0f];
    [UIView commitAnimations];
    self.navigationItem.rightBarButtonItem = BARBUTTON(@"Fade In", @selector(fadeIn:));
}

- (void) fadeIn: (id) sender
{
    CGContextRef context = UIGraphicsGetCurrentContext();
    [UIView beginAnimations:nil context:context];
    [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
    [UIView setAnimationDuration:1.0];
    [[self.view viewWithTag:999] setAlpha:1.0f];
    [UIView commitAnimations];
    self.navigationItem.rightBarButtonItem = BARBUTTON(@"Fade Out", @selector(fadeOut:));
}