MJCPlainFlowLayout

###流水布局

####用法代码

MJCPlainFlowLayout *layout = [[MJCPlainFlowLayout alloc]init];
layout.itemCount = 2;//每行的数量
layout.itemLeftMargin = 10;//最左边间距
layout.itemRightMargin = 10;//最右边间距
layout.itemTopMargin = 10;//最顶部间距
layout.itemBottomMargin = 20;//最底部间距
layout.itemLineMargin = 40;//列间距
layout.itemRowMargin = 10;//行间距
layout.headerReferenceSize = CGSizeMake(self.view.frame.size.width,50);
[self.collectionView1 setCollectionViewLayout:layout];