Oops, I forgot to initialize sectionItemAttributes
Oops, I forgot to initialize sectionItemAttributes

cstars135/CHTCollectionViewWaterfallLayout,BlessNeo/CHTCollectionViewWaterfallLayout,iguchunhui/CHTCollectionViewWaterfallLayout,goodheart/CHTCollectionViewWaterfallLayout,809848367/CHTCollectionViewWaterfallLayout,SummerHanada/CHTCollectionViewWaterfallLayout,809848367/CHTCollectionViewWaterfallLayout,imjerrybao/CHTCollectionViewWaterfallLayout,chiahsien/CHTCollectionViewWaterfallLayout,BlessNeo/CHTCollectionViewWaterfallLayout,tianxiao12345/CHTCollectionViewWaterfallLayout,goodheart/CHTCollectionViewWaterfallLayout,cstars135/CHTCollectionViewWaterfallLayout,iguchunhui/CHTCollectionViewWaterfallLayout,SummerHanada/CHTCollectionViewWaterfallLayout,imjerrybao/CHTCollectionViewWaterfallLayout,boherna/CHTCollectionViewWaterfallLayout,chiahsien/CHTCollectionViewWaterfallLayout,lonelyplanet/TE-CHTCollectionViewWaterfallLayout,tianxiao12345/CHTCollectionViewWaterfallLayout