NSParagraphStyle line spacing ignored

Question

A simple test that is failed: Make a new project with just one subview (UITextView) and put the following in:

- (void)viewDidLoad
{
    [super viewDidLoad];         


        

Answer 1

This is a bug in NSHTMLWriter which is the private class which UITextView uses to convert attributedText into HTML. Internally it displays this HTML via a UIWebDocumentView. Read more on the inner workings of UITextView in my writeup here: http://www.cocoanetics.com/2012/12/uitextview-caught-with-trousers-down/

The problem comes from an easy to miss speciality in the font CSS shorthand. If you specify a pixel size with the font shorthand then this sets BOTH the font-size as well as the line-height. Since NSHTMLWriter puts the font AFTER the line-height this causes the line-height to be cancelled out by the font size.

See here for my Radar which includes the full analysis of the bug: http://www.cocoanetics.com/2012/12/radar-uitextview-ignores-minimummaximum-line-height-in-attributed-string/

I suggest you file a bug report as well and mention my Radar #12863734.