Returns the appropriate line break when the character at the index won’t fit on the same line as the character at the beginning of the range.
- macOS 10.0+
The index in the attributed string.
Returns the index of the closest character before
a, that can be placed on a new line when laying out text. Returns
NSNot if no line break is possible before
index or any part of
a lies beyond the end of the receiver’s characters.