Calculating multiline text height for UILabel/UITableViewCell: different results when calculating vs actual drawing

Question

This general topic has been asked here multiple times: how to render UITableViewCells with varying amount of text and thus varying height. The canonical answer is: you calculate

Answer 1

Of course, the solution is obvious 30 seconds after posting. Maybe useful to others too...

The size by sizeWithFont: was correct. The sizes I calculated in the above way were incorrect, because [label sizeToFit] reduces the width of the label's frame. At subsequent calls to the same code, it started off with the frame that may already have been reduced.

The fix was to simply reset the frame width to a known good width before sizing to fit:

CGRect labelFrame = label.frame;
labelFrame.size.width = 310;
label.frame = labelFrame;
[label sizeToFit];