How to find out width of truncated UILabel text

问题

I have UILabel, which contains dynamic text. Sometimes text is too long to be shown and thus automagically truncated. How do I find out width of the visible part of truncated text?

sizeThatFits returns length of untruncated text, so at the moment I can only detect when truncation will be done. Need to know how much is visible, including those three dots. Any tips?

Clarification: when text is truncated, it's usually shorter than UILabel width.

回答1:

Robot K is correct.

If I was you I'd do the following:

  UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 200, 24)];
  label.text = @"this is some really long text that i want in a small label";
  [view addSubview:label];

  CGSize size = [label.text sizeWithFont:label.font constrainedToSize:label.frame.size  
                 lineBreakMode:label.lineBreakMode];

This should give you a value less than 200 (taking into account the constrained max size and truncation method).

回答2:

I don't understand why the width would be different that the width of the UILabel if the text is being truncated. Regardless, you can use sizeWithFont:constrainedToSize: to calculate the size of a string with a given font but limited to a "constraining size".

来源：https://stackoverflow.com/questions/3903772/how-to-find-out-width-of-truncated-uilabel-text