CGRectrect = [tableViewrectForRowAtIndexPath:indexPath];
/// 获取当前cell 相对于self.view 当前的坐标
rect.origin.y = rect.origin.y- [tableViewcontentOffset].y;
cell 中的图片frame处理：
CGRectimageViewRect = imageView.frame;
imageViewRect.origin.y= rect.origin.y+ imageViewRect.origin.y;
