使UIButton的子view不影响button的点击事件
UIButton* btn = [UIButton buttonWithType:UIButtonTypeCustom];
UIView* subView = [[UIView alloc] init];
subView .userInteractionEnabled = NO;
[btn addSubview:subView];
UIView* subView = [[UIView alloc] init];
subView .userInteractionEnabled = NO;
[btn addSubview:subView];