iOS常用知识

1. 解决成员变量block循环

__weak typeof(self) weakSelf = self;
 __strong typeof(weakSelf) strongSelf = weakSelf;

用strongSelf修饰的self 必须为 __weak 修饰过以后的self
strongSelf->解决成员变量，block循环引用

2. 重写hittest

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
    for (UIView *subview in [self.subviews reverseObjectEnumerator]) {

        CGPoint convertedPoint = [subview convertPoint:point fromView:self];
        UIView *hitTestView = [subview hitTest:convertedPoint withEvent:event];
        if (hitTestView) {
            return hitTestView;
        }
    }
    return [super hitTest:point withEvent:event];
}

3. 移除某个view的手势加在另一个上

//移除scrollViewA原有手势操作
NSMutableArray *list = [NSMutableArray arrayWithArray:scrollViewA.gestureRecognizers];
    for (UIGestureRecognizer *gestureRecognizer in list) {
        [scrollViewA removeGestureRecognizer:gestureRecognizer];
}

//将scrollViewB的手势操作加到scrollViewA中
for (UIGestureRecognizer *gestureRecognizer in scrollViewB.gestureRecognizers) {
        [scrollViewA addGestureRecognizer:gestureRecognizer];
}