Don't observe the note annotation, rather pass KVO notifications explicitly. This avoids a crash in dealloc. 
Don't observe the note annotation, rather pass KVO notifications explicitly. This avoids a crash in dealloc. 

JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim,JackieXie168/skim