NSAttributedString highlight/background color shows between lines (ugly)

Question

I'm trying to nicely display paragraphs of highlighted in a NSTextView. Right now, I'm doing this by creating a NSAttributedString with a background color. Here's some simplified code:

NSDictionary *attributes = @{NSBackgroundColorAttributeName:NSColor.greenColor};
NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"Here is a single line of text with single spacing" attributes:attributes];

[textView.textStorage setAttributedString:attrString];

This approach basically works, in that it produces highlighted text.

Unfortunately, when multiple lines exist, the highlight covers the vertical space between the lines in addition to the lines themselves, resulting in ugliness.

Does anyone know of a way to do this kind of highlighting in Cocoa? The picture below is basically what I'm looking for (ignore the shadow on the white boxes):

I'd be willing to use CoreText, html, or whatever is necessary to make things look nicer.

Answer 1

You will need to subclass NSLayoutManager and override:

- (void)fillBackgroundRectArray:(const CGRect *)rectArray
                      count:(NSUInteger)rectCount
          forCharacterRange:(NSRange)charRange
                      color:(UIColor *)color;

This is the primitive method for drawing background color rectangles.