一个自定义瀑布流框架
- (CGFloat)waterflowLayout:(WaterflowLayout *)waterflowLayout heightForItemAtIndex:(NSUInteger)index itemWidth:(CGFloat)itemWidth
- (CGFloat)rowMarginInWaterflowLayout:(WaterflowLayout *)waterflowLayout;
- (CGFloat)columnMarginInWaterflowLayout:(WaterflowLayout *)waterflowLayout;
- (CGFloat)columnCountInWaterflowLayout:(WaterflowLayout *)waterflowLayout;
- (UIEdgeInsets)edgeInsetsInWaterflowLayout:(WaterflowLayout *)waterflowLayout;