停止scrollview的惯性滑动

- (void)scrollViewDidEndDragging:(UIScrollView*)scrollView willDecelerate:(BOOL)decelerate {
  if(decelerate) {
     dispatch_async(dispatch_get_main_queue(), ^{
     printf("STOP IT!!\n");
     [scrollViewsetContentOffset:scrollView.contentOffsetanimated:NO];**
            });
      }
}