How do I get -[NSString sizeWithFont:forWidth:lineBreakMode:] to work?

Question

I updated my question \"Sizing a UILabel (in the iPhone SDK) to fit?\" with a description of my problem with a suggested solution, but didn\'t get an answer. Perhaps I\'ll

Answer 1

That height is in pixels. I expect it's truncating, i.e. giving you the metrics you'd see if you set this text on a UILabel with 1 line.

Try using sizeWithFont:constrainedToSize: and just give it MAXFLOAT for the height component of the size.

Answer 2

As anyone who has puzzled this out learns, the method is inappropriately named and rather inconsistent with what you'd expect (that's a violation of good API design, but as any seasoned dev knows: Apple's API is not well designed, sorry guys). Worth reading: Josh Bloch's presentation on good API design.

I'd posit that they should rename it (if it must be kept) and make this one useful, such that you don't end up using the common practice of passing in a CGSize with a size you know is much too large.

[someString sizeWithFont:yourFont 
       constrainedToSize:CGSizeMake(maxWidthYouSpecify, self.frame.size.height)  
           lineBreakMode:UILineBreakModeWordWrap];

Alternately this would work just as well:

[someString sizeWithFont:yourFont 
       constrainedToSize:CGSizeMake(maxWidthYouSpecify, CGFLOAT_MAX)
           lineBreakMode:UILineBreakModeWordWrap];

This is, arguably, how the function should work. (FWIW, CGFLOAT_MAX is defined in CGGeometry)

An aside, but rather important: all Core Graphics deal in points not pixels.

One point does not necessarily correspond to one pixel on the screen.

That's an important distinction and one you need to understand when dealing with different resolutions (iPhone 3GS vs 4 vs iPad, etc). See Apple's docs and Command+F for "Points vs Pixels".