Clever Geek Handbook

Why is UICollectionView with UICollectionViewFlowLayout not showing cells but asking for size?

Why collectionview with flow layout sometimes doesn't show cells, but delegate asks for size and section counters and responder give correct information.

Here is an example, problem with 6 sections

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

Since u can see in numberOfItemsInSection (ASKED, RETUR), 1 item is returned in 6 section

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

After that, sizeForItemAtIndexPath for item 0 in section 6 returns the size

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

But then the collectionview asks for a cell not being called for section 6

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


I found a solution!

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


If you see your cell disappear where it should be, check your dimensions!

If any border size is zero, it will break the CollectionViewFlowLayout from working properly.

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