iOS Assertion Failure in UICollectionView

Question

I'm getting the error ...

*** Assertion failure in -[UICollectionView _dequeueReusableViewOfKind:withIdentifier:forIndexPath:], /SourceCache/UIKit/UIKit-2372/UICollectionView.m:2249

When trying to display a UICollectionView.

The lines causing it are...

static NSString *CellIdentifier = @"Cell";

UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];

Error happening on the dequeue.

There are no other errors so I'm struggling to know where to begin with this.

Can anyone shed light on this?

Answer 1

Make sure that if you use the registerNib: method:

UINib *nibH = [UINib nibWithNibName:HEADER_ID bundle:nil];
[collectionView registerNib:nibH
 forSupplementaryViewOfKind:UICollectionElementKindSectionHeader 
        withReuseIdentifier:HEADER_ID];

that ALSO in the nib file, when you select the top-level collection reusable view, use the attributes inspector, and make sure the Identifier is set to the same value you are passing in to the withReuseIdentifier: parameter.

Answer 2

Replace

NSString *CellIdentifier = @"Cell";

with

static NSString *CellIdentifier = @"Cell";

Answer 3

I got this crash on iOS 9 only (iOS 10/11 are working fine).

I had no custom subclass of a Flow Layout but setting the headerReferenceSize on the existing one directly. So in Interface Builder with Section Header enabled I got this crash, without the checkmark everything works fine and the headers are being displayed correctly, since I set the size in code.

Answer 4

You need to register like below:

[self.collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"MY_CELL"];

Answer 5

Been reading the docs (should possibly have done this first :) )

Anyway, the collectionView I am using is within a separate xib file (not a storyboard) and from the docs...

Important: You must register a class or nib file using the
registerClass:forCellWithReuseIdentifier: or
registerNib:forCellWithReuseIdentifier: method before calling this method.

Thanks

Answer 6

I had the same problem. Here's how I solved it.

Move

[self.pictureCollectionView registerNib:[UINib nibWithNibName: bundle:nil] forCellWithReuseIdentifier:reuseID]

to be in - (void)viewDidLoad,

rather than method - (void)awakeFromNib.