为什么UICollectionView与UICollectionViewFlowLayout不显示单元格，但要求大小？

为什么使用stream布局的collectionview有时不显示单元格，但是代表请求的大小，以及部分项目数和响应者提供正确的信息。

这里的例子，6节的麻烦

2015-04-08 04:43:59.020 ASKED SECTION:0 ITEMS:0 2015-04-08 04:43:59.023 RETUR SECTION:0 ITEMS:1 2015-04-08 04:43:59.023 ASKED SECTION:1 ITEMS:0 2015-04-08 04:43:59.024 RETUR SECTION:1 ITEMS:1 2015-04-08 04:43:59.024 ASKED SECTION:2 ITEMS:0 2015-04-08 04:43:59.024 RETUR SECTION:2 ITEMS:1 2015-04-08 04:43:59.024 ASKED SECTION:3 ITEMS:0 2015-04-08 04:43:59.024 RETUR SECTION:3 ITEMS:1 2015-04-08 04:43:59.025 ASKED SECTION:4 ITEMS:0 2015-04-08 04:43:59.043 RETUR SECTION:4 ITEMS:0 2015-04-08 04:43:59.043 ASKED SECTION:5 ITEMS:0 2015-04-08 04:43:59.043 RETUR SECTION:5 ITEMS:0 **2015-04-08 04:43:59.043 ASKED SECTION:6 ITEMS:0** **2015-04-08 04:43:59.044 RETUR SECTION:6 ITEMS:1** 2015-04-08 04:43:59.044 ASKED SECTION:7 ITEMS:0 2015-04-08 04:43:59.044 RETUR SECTION:7 ITEMS:8 2015-04-08 04:43:59.045 ASKED SECTION:8 ITEMS:0 2015-04-08 04:43:59.046 RETUR SECTION:8 ITEMS:0 2015-04-08 04:43:59.046 ASKED SECTION:9 ITEMS:0 2015-04-08 04:43:59.046 RETUR SECTION:9 ITEMS:2 2015-04-08 04:43:59.049 SIZE_ SECTION:0 ITEM:0 SIZE:320x70 2015-04-08 04:43:59.052 SIZE_ SECTION:1 ITEM:0 SIZE:320x70 2015-04-08 04:43:59.053 SIZE_ SECTION:2 ITEM:0 SIZE:320x0 2015-04-08 04:43:59.053 SIZE_ SECTION:3 ITEM:0 SIZE:320x246.1538 **2015-04-08 04:43:59.053 SIZE_ SECTION:6 ITEM:0 SIZE:320x80** 2015-04-08 04:43:59.055 SIZE_ SECTION:7 ITEM:0 SIZE:320x139 2015-04-08 04:43:59.057 SIZE_ SECTION:7 ITEM:1 SIZE:320x139 2015-04-08 04:43:59.062 SIZE_ SECTION:7 ITEM:2 SIZE:320x79 2015-04-08 04:43:59.066 SIZE_ SECTION:7 ITEM:3 SIZE:320x79 2015-04-08 04:43:59.069 SIZE_ SECTION:7 ITEM:4 SIZE:320x79 2015-04-08 04:43:59.072 SIZE_ SECTION:7 ITEM:5 SIZE:320x79 2015-04-08 04:43:59.075 SIZE_ SECTION:7 ITEM:6 SIZE:320x79 2015-04-08 04:43:59.079 SIZE_ SECTION:7 ITEM:7 SIZE:320x79 2015-04-08 04:43:59.079 SIZE_ SECTION:9 ITEM:0 SIZE:139x139 2015-04-08 04:43:59.080 SIZE_ SECTION:9 ITEM:1 SIZE:139x139 2015-04-08 04:43:59.082 CELL_ SECTION:0 ITEMS:0 2015-04-08 04:43:59.087 CELL_ SECTION:1 ITEMS:0 

正如你可以看到numberOfItemsInSection（ASKED，RETUR）在6节返回1项

2015-04-08 04：43：59.044 RETUR SECTION：6项目：1

之后在sizeForItemAtIndexPath中为6个部分中的0项返回大小

2015-04-08 04：43：59.053 SIZE_ SECTION：6 ITEM：0 SIZE：320×80

但是，然后collectionview要求单元格，不要求第6节

 2015-04-08 04:43:59.082 CELL_ SECTION:0 ITEMS:0 2015-04-08 04:43:59.087 CELL_ SECTION:1 ITEMS:0 

Answer 1

我find解决scheme！

 2015-04-08 04:43:59.053 SIZE_ SECTION:2 ITEM:0 SIZE:320x0 

如果你看到你的细胞消失，他们必须可见，检查你的尺寸！

如果任何边框大小将为零，则正确工作CollectionViewFlowLayout。