Memoryleaks

[zhongwuzw]

revert code

[MillmanY]

you can't remove (index >= shitIdx-2) if you have lots of cell will very slow because of cell in the rect of screen

[zhongwuzw]

Yep, you can just add frame set when index < shitIdx-2,like add frame calculate

[zhongwuzw]

By Instruments,I found the reason of frame drop is not attribute generate(ps. we can cache the attribute object,other than create new attribute object every layout loop),but offscreen-Rendered:

        self.layer.shadowOffset = offset
        self.layer.shadowOpacity = opacity
        self.layer.shadowColor = UIColor.black.withAlphaComponent(0.5).cgColor