When debugging autolayout what is the meaning of the autoresizing mask strings such as h=–& v=-&-?

If you specify autoresizing masks instead of constraints, or specify no constraints at all, then the view will have NSAutoResizingMaskLayoutConstraint constraints as opposed to NSLayoutConstraints. If you set translatesAutoresizingMaskIntoConstraints to NO, then these constraints do not appear. You can’t mix and match on a single view, or you get unsatisfiable constraint errors.

I set up a quick test project with various combinations of autoresizing masks and the logging format is pretty straightforward.

• h= or v= indicates that we are talking about contraints in the horizontal or vertical direction.
• - indicates a fixed size
• & indicates a flexible size
• The order of symbols represents margin, dimension, margin

Therefore, h=&-& means you have flexible left and right margins and a fixed width, v=-&- means fixed top and bottom margins and flexible height, and so forth.