Autolayout problems with iOS8 with code that works fine on iOS7

@robmayoff has a great answer for this: https://stackoverflow.com/a/26066992/1424669

Essentially, in iOS8 you can no longer call setNeedsUpdateConstraints and setNeedsLayout on a view and expect the constraints of subviews to update.

You must call these methods on the view whose constraint is changing. This is backwards compatible to iOS7.

EXAMPLE:

Suppose you have a ViewController with root view self.view and a subview called containerView. containerView has a NSLayoutConstraint attached to it that you want to change (in this case, top space).

In iOS7 you could update all constraints in a VC by requesting a new layout for the root view:

self.containerView_TopSpace.constant = 0;
[self.view setNeedsUpdateConstraints];
[self.view setNeedsLayout];

In iOS8 you need to request layouts on the containerView:

self.containerView_TopSpace.constant = 0;
[self.containerView setNeedsUpdateConstraints];
[self.containerView setNeedsLayout];

You might find the answers to this question helpful: UICollectionView cell subviews do not resize

In most cases the works in iOS7 but not on iOS 8 auto layout problems seem to stem from the root view not being sized correctly in iOS 8, particularly when we set translatesAutoresizingMaskIntoConstraints to NO. For my views I was able to set the root view's frame in layoutSubviews (or whichever appropriate initializer that does have the correct bounds) and this resolved the issue.

self.contentView.frame = CGRectInset(self.bounds, 0, 0);

As shown in the answer above, you could also do

self.contentView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;

and then turn translatesAutoresizingMaskIntoConstraints back to NO before you start setting your own constraints in code.

Definitely hate that so much of our time is taken with these annoying gotchas.