// 分配每行的item - (UIView *)dropBoxView : (XMFDropBoxView *)dropBoxView itemAtIndex : (NSUInteger)index; // 每行item的高度 - (CGFloat)dropBoxView:(XMFDropBoxView *)dropBoxView heightForItemAtIndex:(NSUInteger)index; // 一共item数量 - (NSUInteger)numberOfItemInDropBoxView : (XMFDropBoxView *)dropBoxV