Gets the range of characters that originally spawned the glyphs in the line.
- iOS 3.2+
- macOS 10.5+
- Mac Catalyst 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
- Core Text
The line from which to obtain the string range.
CFRange structure that contains the range over the backing store string that spawned the glyphs, or if the function fails for any reason, an empty range.