设置ScrollView滚动到顶

新建UIView分类

- (void)setSubScrollsToTop:(BOOL)scrollsToTop{
    [[self subviews] enumerateObjectsUsingBlock:^(UIView *obj, NSUInteger idx, BOOL *stop) {
        if ([obj isKindOfClass:[UIScrollView class]]) {
            [(UIScrollView *)obj setScrollEnabled:scrollsToTop];
            *stop = YES;
        }
    }];
}