iPhone/iPad - Core Animation - CGAffineTransformMakeTranslation doesn't modify the frame

Question

I'm facing a very annoying problem. Here's the context : I have a "rectangle" view which is the subview of the main view. What i'm trying to do is simple, when I click on a button, I want the "rectangle" view to translate on the x-axis in order to disappear. I then add a new subview and translate it in order to take the place of the previous "rectangle" view. It's work fine except that if I press the button again, the animation will begin off the screen, like the CGAffineTransformMakeTranslation didn't change the frame of my new "rectangle" view. Here's the code :

UIView *rectangleView = [detailView viewWithTag:4]; //the actual frame is (20.0, 30.0, 884.0, 600.0)

[UIView animateWithDuration:0.5 animations:^{
    [rectangleView setTransform:CGAffineTransformMakeTranslation(-1000, 0)];
} completion:^(BOOL finished) {
    [rectangleView removeFromSuperview];
    UIView *otherView = [[UIView alloc] initWithFrame:CGRectMake(1020.0, 30.0, 884.0, 600.0)];
    [otherView setBackgroundColor:[UIColor purpleColor]];
    [otherView setTag:4];
    [detailView addSubview:otherView];
    [UIView animateWithDuration:0.5 animations:^{
        [otherView setTransform:CGAffineTransformMakeTranslation(-1000, 0)];
    } completion:^(BOOL finished) {
        [otherView release];
    }];
}];

Answer 1

After your second view is added you already set its transform to be equal to CGAffineTransformMakeTranslation(-1000, 0), and when you want to remove that view you set exactly the same transform - so it will have no effect. You have 2 options here:

1. Apply translation to the transform the view already has:

   CGAffineTransform newTransform = CGAffineTransformConcat(rectangleView.transform, CGAffineTransformMakeTranslation(-1000, 0));
   [rectangleView setTransform:newTransform];
   

2. Instead of applying transforms operate with view position directly (e.g. via its center property)

   UIView *rectangleView = [detailView viewWithTag:4]; //the actual frame is (20.0, 30.0, 884.0, 600.0)
   CGAffineTransform tf = CGAffineTransformMakeTranslation(-1000, 0);
   [UIView animateWithDuration:0.5 animations:^{
       [rectangleView setCenter: CGPointApplyAffineTransform(rectangleView.center, tf)];
   } completion:^(BOOL finished) {
       [rectangleView removeFromSuperview];
       UIView *otherView = [[UIView alloc] initWithFrame:CGRectMake(1020.0, 30.0, 884.0, 600.0)];
       [otherView setBackgroundColor:[UIColor purpleColor]];
       [otherView setTag:4];
       [detailView addSubview:otherView];
       [UIView animateWithDuration:0.5 animations:^{
           [otherView setCenter: CGPointApplyAffineTransform(otherView.center, tf)];
       } completion:^(BOOL finished) {
           [otherView release];
       }];
   }];