How to animate NSLayoutConstraint without IBOutlet - ios

Question

I have a View Controller containing a view (of another controller) and a tab bar at the bottom. I want to add an iAD banner such that when an ad is loaded and unloaded, the contained view is resized accordingly.
/* AutoLayout */
/* pin Left of child to left of parent */
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:child.view
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeft
multiplier:1.0
constant:0]];
/* pin Right of child to right of parent */
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:child.view
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeRight
multiplier:1.0
constant:0]];
/* pin top of child to bottom of nav bar(or status bar if no nav bar) */
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:child.view
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.topLayoutGuide
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0]];
/* pin Top of tab bar to bottom of child view */
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.bottomLayoutGuide
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:child.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0]];
/*
* adConstraint is an instance variable to hold the constraint I want to animate
* Note that it is not an IBOutlet
*/
adConstraint = [NSLayoutConstraint constraintWithItem:child.view
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1.0
constant:0];
[self.view addConstraint:adConstraint];
In my delegate methods i have the following
- (void)bannerViewDidLoadAd:(ADBannerView *)banner
{
UIView animateWithDuration:1 animations:^{
adConstraint.constant = -banner.frame.size.height;
[self.view layoutIfNeeded];
}];
}
and
- (void)bannerView:(ADBannerView *)banner didFailToReceiveAdWithError:(NSError *)error
{
UIView animateWithDuration:1 animations:^{
adConstraint.constant = 0;
[self.view layoutIfNeeded];
}];
}
I seriously need help with this! Is it even possible to achieve this without Storyboard and the IBOutlet or am I doing something (terribly) wrong?
Please Help?!
*********************** EDIT: ************************
I've noticed a problem; The ad shows up but bannerDidLoadAd is not called. I know this because I added log statements in it. Does anyone know why this might be happening????

Answer 1

Try calling
[self.view setNeedsUpdateConstraints];
before
[self.view layoutIfNeeded];
It should work!
[UIView animateWithDuration:1 animations:^{
adConstraint.constant = 0;
[self.view setNeedsUpdateConstraints];
[self.view layoutIfNeeded];
}];