tableview修改selectedBackgroundView的frame

思路

1. selectedBackgroundView的frame无法修改，但可以替换
2. 在替换的view上加上view，并设置这个view的frame

代码

 UIView* selectBackview = [[UIView alloc] init];        selectBackview.backgroundColor = [UIColor clearColor];        UIView* backview = [[UIView alloc] initWithFrame:cell.mainView.frame];        backview.backgroundColor = RGBAlphaColor(183,207,232,0.4);        [selectBackview addSubview:backview];        cell.selectedBackgroundView = selectBackview;

效果图