ios - Change UILabel postion animated using constraints from left to the right

Question

I am using this code:

- (void)replaceTopConstraintOnView:(UIView *)view withConstant:(float)constant
{
    [[[self contentView] constraints] enumerateObjectsUsingBlock:^(NSLayoutConstraint *constraint, NSUInteger idx, BOOL *stop) {
        if ((constraint.firstItem == view) && (constraint.firstAttribute == NSLayoutAttributeLeft)) {
            constraint.constant = constant;
        }
    }];
}

when I set text in my label I change constraint from the -100 to 10.

- (void)setText:(NSString *)text
{
    [[self label] setText:text];

    [self replaceTopConstraintOnView:[self label] withConstant:10];
    [[self contentView] layoutIfNeeded];
}

Here is how I configure label constarint at initialization:

Init of table view cell method:

UILabel *label = [[UILabel alloc] initWithFrame:CGRectZero];

[label setTranslatesAutoresizingMaskIntoConstraints:NO];


[NSLayoutConstraint constraintWithItem:[self label]
                                        attribute:NSLayoutAttributeLeft
                                        relatedBy:NSLayoutRelationEqual
                                           toItem:[self containerView]
                                        attribute:NSLayoutAttributeLeft
                                       multiplier:1.0f
                                         constant:-100];

So it does not work for me. I don't describe animation here. But it even does not work without UIView animation block. I've debuted it the constraints constant was changed to 10 but I still don't see label. So the label also has width and hight. And If I set constraint to 10 at start I see my label.