Porting changes made on main branch in commit 94dd5216a1220aafcf06b995b2caff82fb6c4a27.
Porting changes made on main branch in commit 94dd5216a1220aafcf06b995b2caff82fb6c4a27.

Ensure that labels can be drawn on iOS6 without crashing.

DmitryNek/EFCircularSlider,sidorov-panda/EFCircularSlider,SatoTakeshiX/EFCircularSlider,neonaldo/EFCircularSlider,eliotfowler/EFCircularSlider,AlexanderMazaletskiy/EFCircularSlider,matthewyan/EFCircularSlider,glt3953/EFCircularSlider-glt3953,rainkong/EFCircularSlider