CollisionBehaviour do not working with autolayout

Question

I am trying to implement collisions between two views.

firstView is view with textfields. If some textfield became firstRecognizer and keyboard frame overlap firstView . It moves up and if firstView collides with secondView , it should push it up too. But this does not happen. Instead firstView moves up until collides with secondView and then puts back on old place.

Here code, which I use:

- (void) keyboardChangeValueWithFrame:(CGRect)keyboardFrame isOpening:(BOOL)isOpening isClosing:(BOOL)isClosing {
    CGFloat animTime = .3f;
    if (isOpening && !isClosing) {
        CGRect authFillerViewFrame = self.regFillerView.frame;
        CGFloat rectDif = keyboardFrame.origin.y - authFillerViewFrame.origin.y - authFillerViewFrame.size.height;
        if ([_animator.behaviors containsObject:_collision]) {
            [_animator removeBehavior:_collision];
        }
        if (rectDif < 0) {
            [self.view layoutIfNeeded];
            self.regFillerViewHorizCenterConst.constant = rectDif;
            [self.logoView layoutIfNeeded];
            [UIView animateWithDuration:animTime animations:^{
                _collision = [[UICollisionBehavior alloc] initWithItems:@[self.regFillerView, self.logoView]];
                _collision.translatesReferenceBoundsIntoBoundary = NO;
                _collision.collisionDelegate = self;
                _collision.collisionMode = UICollisionBehaviorModeItems;
                [_animator addBehavior:_collision];
                _collision.action = ^{

                };
                [self.view layoutIfNeeded];
            } completion:^(BOOL finished) {
                if (finished) {
                    //
                }
            }];
        }
    } else if (!isOpening && isClosing) {
        [self.view layoutIfNeeded];
        self.regFillerViewHorizCenterConst.constant = 0.f;
        [UIView animateWithDuration:animTime animations:^{
            [self.view layoutIfNeeded];
        } completion:^(BOOL finished) {
            //
        }];
    }
}

Could somebody tell my mistake? Or, may be somebody know better solution?

Answer 1

I found solution. My mistake was to add collision behaviour to animator before calling layoutIfNeeded . Now I call layoutIfNeeded before adding collision behaviour and it works well.

[UIView animateWithDuration:animTime animations:^{
                _collision = [[UICollisionBehavior alloc] initWithItems:@[self.regFillerView, self.logoView]];
                [self.view layoutIfNeeded];
                _collision.translatesReferenceBoundsIntoBoundary = NO;
                _collision.collisionDelegate = self;
                _collision.collisionMode = UICollisionBehaviorModeItems;
                [_animator addBehavior:_collision];
                _collision.action = ^{

                };
            } completion:^(BOOL finished) {
                if (finished) {
                    //
                }
            }];