Q:

Auto-Layout Constraint: When resizing, distributes the space non-equally to the subviews?

It might be easiest to demonstrate my question with an example, so here it goes:
I have a container view, which has two subviews, A and B.
Container: 240x80
A: 80x80, pinned leading/top/bottom spacing.
B: 160x80, pinned leading/top/bottom spacing, pinned h spacing with A.

Now, when I resize the container to, say, 480x80, I got something like this:

That is because Xcode thinks my constrains are ambiguous, so it pinned A's width for me and gives all additional horizontal space to B. 
Ok, I understand its concern, but what I really want is to have both A and B resize proportionally, like this:

My hunch is that it'll have something to do with the Hugging/Compression Resistance Priority settings, but I can't figure out how to set those values to get the results I want!
To put this question in an other way, when the container is enlarged, how do I specify where the extra space go? How do I set the priorities so that the space distributes to view A and view B 4:6? 5:5? 8:2?
Thanks! 

A:

This is very similar to the other question you just asked. Make a constraint that makes the width of one view equal to the other with a multiplier to get the ratio you want:
NSLayoutConstraint *con = [NSLayoutConstraint constraintWithItem:self.viewA attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self.viewB attribute:NSLayoutAttributeWidth multiplier:0.5 constant:0];

This constraint need to be added to the superview of views A and B.

A:

Not that the provided answer is unworthy but you should be able to do this now in Xcode (5.1.1) by creating an equal width constraint between view A and view B and setting a multiplier.
To do that, remove any other width constraints you might have between these two views then control drag from view A to view B and choose an Equal Widths constraint. Select that constraint from the Document Outline view and then in the inspector, change the Multiplier to the ratio you want. In your case it looks like it might be 1:3, or something close that. Here's what my view might look like:

And what the inspector should look like:

Just play with the ratios, until you get it right.

