Add property minimumLineHeight and maximumLineHeight.
Remove all setNeedDisplay. If you want update, do this manual.
Fix the bug when mix Chinese and English lineheight error. Now draw line
offset y as -(font.descender+line descent). It's offset from label baseline.
If you want fix linespace bug when mix Chinese & English, set leading = -100 and maximumLineHeight = minimumLineHeight = font.lineHeight.
Make sure TTTLabel draw after Cell draw, and make sure setNeedsDisplay every time. Such as tableview reuse.
add test Text
set:
self.attributedLabel.leading = -100;
self.attributedLabel.maximumLineHeight = f.lineHeight;
self.attributedLabel.minimumLineHeight = f.lineHeight;