Returns the glyph at the specified index.
- iOS 7.0+
- macOS 10.11+
- tvOS 9.0+
The index of the glyph that you want. If the index is out of range, this method raises an exception with the error
The glyph at the specified index.
Calling this method generates all of the glyphs (as needed) up to and including the glyph at the specified index.