[iOS]: Auto layout animate change of frame position when removing and adding constraints

Question

I have a complex autolayout which needs to adapt to rotation by removing old constraints and adding new ones.

I have a grid layout of views inside a containerView.

The problem is when I call

  [UIView animateWithDuration:0.4 animations:^{
            [self.containerView layoutIfNeeded];
    }];

The views always animate from the position [0,0] to their new position. What I would prefer is that the views would move from their old position (before I remove the constraints) to the new positions (after removal and addition of the new constraints)

Has someone been able to achieve this?

How about adding the constraint manipulation to the animation block? — David Berry, May 01 '14 at 15:42
Are you doing this in `viewDidLoad`? The initial constraints have not yet been applied and hence 0,0. If you do this in `viewDidAppear`, you should see them animate from old position to new position. If this is a rotation based animation, in which method are you trying to invoke this? Also, after removing the old constraints, are you doing anything that might trigger the (non-existent) constraints to be applied (which can happen with the most innocuous of actions, such as setting text label)? A little more context about where you've put this code might be helpful. — Rob, May 01 '14 at 15:54

score 1 · Accepted Answer · edited May 23 '17 at 12:32

The following post gave me the hint to make it work:

But not the actual accepted answer but rather:

[UIView animateWithDuration:1.0f delay:0.0f options:UIViewAnimationOptionLayoutSubviews animations:^{
    [self.view layoutIfNeeded];
} completion:nil];

The optional parameter options:UIViewAnimationOptionLayoutSubviews inspired me to try different options and the actual option needed was options:UIViewAnimationOptionBeginFromCurrentState

[UIView animateWithDuration:duration delay:delay options:UIViewAnimationOptionBeginFromCurrentState animations:^{
        [self layoutIfNeeded];
    } completion:nil];

Which allowed the animation to occur from the last position, even if constraints are removed and new ones are added.

[iOS]: Auto layout animate change of frame position when removing and adding constraints

1 Answers1