UILabel not wrapping text correctly sometimes (auto layout)

Question

I have a uilabel setup in a view. It doesn\'t have a width constraint, but its width is instead determined by a leading constraint to the thumbnail image, and a trailing con

Answer 1

I had the same problem and solved it using a suggestion from this answer. In a subclass of UILabel I placed this code:

- (void)layoutSubviews
{
    [super layoutSubviews];
    self.preferredMaxLayoutWidth = self.bounds.size.width;
}

I don't understand why this is not the default behavior of UILabel, or at least why you cannot just enable this behavior via a flag.

I am a little concerned that preferredMaxLayoutWidth is being set in the middle of the layout process, but I see no easy way around that.

Answer 2

Also, check that you are passing integral numbers to your layout constraints in code.

For me it happened that after some calculations (e.g. convertPoint:toView:), I was passing in something like 23.99999997, and eventually this lead to a 2-line label displaying as a one-liner (although its frame seemed to be calculated correctly). In my case CGRectIntegral did the trick!

Rounding errors could kill ya :)

Answer 3

I'm someone who has written an app that uses autolayout of five labels in a cell in a table whose cells have different heights, where the labels resize themselves according to what's in them, and it does work. I'm going to suggest, therefore, that the reason you're having trouble might be that your constraints are under-determining the layout - that is, that you've got ambiguous layout for the elements of the cell. I can't test that hypothesis because I can't see your constraints. But you can easily check (I think) by using po [[UIWindow keyWindow] _autolayoutTrace] when paused in the debugger.

Also I have one other suggestion (sorry to just throw stuff at you): make sure you're setting the label's preferredMaxLayoutWidth. This is crucial because it's the width at which the label will stop growing horizontally and start growing vertically.