How to calculate UILabel width based on text length?

In swift

 yourLabel.intrinsicContentSize().width 

CGSize expectedLabelSize = [yourString sizeWithFont:yourLabel.font 
                        constrainedToSize:maximumLabelSize 
                        lineBreakMode:yourLabel.lineBreakMode]; 

What is -[NSString sizeWithFont:forWidth:lineBreakMode:] good for?

this question might have your answer, it worked for me.

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For 2014, I edited in this new version, based on the ultra-handy comment by Norbert below! This does everything. Cheers

// yourLabel is your UILabel.

float widthIs = 
 [self.yourLabel.text
  boundingRectWithSize:self.yourLabel.frame.size                                           
  options:NSStringDrawingUsesLineFragmentOrigin
  attributes:@{ NSFontAttributeName:self.yourLabel.font }
  context:nil]
   .size.width;

NSLog(@"the width of yourLabel is %f", widthIs);

yourLabel.intrinsicContentSize.width for Objective-C / Swift