切记 : 计算图片的高度和宽度应该在请求数据的时候获取.然后保存起来 否则的话会造成卡顿现象
方法优化:
WidthAndHeight *wAndH = _widthAndHeightDataArray[indexPath.row];
CGFloat width = wAndH.widthPic;
CGFloat height = wAndH.heightPic;
CGRect picBackViewFrame = cell.picBackView.frame;
cell.picBackView.frame = CGRectMake(0, picBackViewFrame.origin.y, SCREEN_WIDTH, SCREEN_WIDTH);
cell.postPhoto.frame = CGRectMake(width / 2 > SCREEN_WIDTH ? 0 : ((SCREEN_WIDTH - width / 2) / 2), height / 2 > SCREEN_WIDTH ? 0 : ((SCREEN_WIDTH - height / 2) / 2), width / 2 > SCREEN_WIDTH ? SCREEN_WIDTH : (width / 2), height / 2 > SCREEN_WIDTH ? SCREEN_WIDTH : (height / 2));
计算图片的宽和高 动态设置图片的位置
原文：http://www.cnblogs.com/tian-sun/p/4849723.html
