如何在不使用两个视图控制器的情况下为两个视图之间的过渡设置动画？

Question

I am trying to simulate a deck of cards, where a swipe over the screen makes the next card enter the display from the right, covering the card that is currently visible. I know how to program this using two view controllers and custom segues, but I want to keep it simple. I therefore want to stay within one and the same view controller, copy the current view into a temporary view, draw the new view, and then animate the new view to drift in from the right and cover the old one. Here's my attempt:

- (IBAction)SwipeLeft:(id)sender
{   UIView *sv = self.view;
    [self Layout]; // this is where the next card is drawn
    UIView *dv = self.view;

    dv.center = CGPointMake(sv.center.x + sv.frame.size.width, sv.center.y);
    sv.center = CGPointMake(sv.center.x, sv.center.y);

    [UIView animateWithDuration:0.3
                     animations:^
     {   dv.center = CGPointMake(sv.center.x, sv.center.y);
         sv.center = CGPointMake(sv.center.x - sv.frame.size.width, sv.center.y);
     }];

    NSLog(@"Swipe left");
}

When I run this code, I do see the new card enter the screen appropriately, however, the 'old' view dissappears immediately and turns into a black screen before the animation starts.

How can I correct this?

Answer 1

Clearly this code does not work, as both pointers point at the same memory location. I decided to solve my problem in a different way. Rather than trying to copy a View object, I create a screen shot, copy the UIImage into a View object, cover the screen under the copy of the old screen when I draw the new screen and than animate that View object. Probably a smarter solution. It works great.