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 (eg 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]; }]; }]; 

Answer 2

Try animating the center property instead of using an affine transform. The transforms are not additive, so your second animation (when your newly added detail view is then moved off the screen) isn't actually altering the view at all, as it already has that translation (-1000,0) applied to it.