UICollectionView and Supplementary View (header)

Question

Trying to add a a Supplementary view into my UICollectionView as a header. I\'m having issues getting it to work.

I use a custom UICollectionViewFlowL

Answer 1

If you look at the error message, it says that the data source is not set. This should fix it:

self.collectionView.dataSource = self;

Make sure your view controller implements the data source protocol:

YourViewController : UIViewController<UICollectionViewDataSource>

Answer 2

I cleaned up my code and removed the UICollectionView I had created in IB and created it all in code. I ran the it again and got a different error and realized I didn't set the delegate or dataSource in IB. I did:

self.collectionView.delegate = self;
self.collectionView.datasource = self;

But that must not have been good enough.

So with UICollectionView created in IB and not setting the delgate/datasource in IB, but rather in the code:

[self.view bringSubviewToFront:self.collectionView];
self.collectionView.collectionViewLayout = collectionViewFlowLayout;
self.collectionView.backgroundColor = [UIColor orangeColor];
self.collectionView.delegate = self;
self.collectionView.dataSource = self;

[self.collectionView registerClass:[DatasetCell class] forCellWithReuseIdentifier:@"cvCell"];

[self.collectionView registerClass:[CollectionHeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"CollectionHeaderView"];

was an issue. I redid it to create the UICollectionView all in code:

UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:collectionViewFlowLayout];
collectionView.translatesAutoresizingMaskIntoConstraints = FALSE;
collectionView.backgroundColor = [UIColor yellowColor];
collectionView.delegate = self;
collectionView.dataSource = self;

[collectionView registerClass:[DatasetCell class] forCellWithReuseIdentifier:@"cvCell"];

[collectionView registerClass:[CollectionHeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"CollectionHeaderView"];

[self.view addSubview:collectionView];

self.collectionView = collectionView;

and i get a different error:

*** Assertion failure in -[UICollectionView _dequeueReusableViewOfKind:withIdentifier:forIndexPath:], /SourceCache/UIKit_Sim/UIKit-2380.17/UICollectionView.m:2249
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'could not dequeue a view of kind: UICollectionElementKindSectionHeader with identifier CollectionHeaderView - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'

which I'll try to figure out.

EDIT:

figured it out, I was registering the header incorrectly:

[collectionView registerClass:[CollectionHeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"CollectionHeaderView"];

switched to:

UINib *headerNib = [UINib nibWithNibName:@"CollectionHeaderView" bundle:nil];

[collectionView registerNib:headerNib forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"CollectionHeaderView"];

and everything works. Not entirely sure how the registerClass: wasn't working though.

Answer 3

I faced with the similar problem, but my app crashed after I programmatically pop my UICollectionViewController. In some reason (I think it's just a bug in SDK) self.collectionView was alive after its' controller destroy, thus causing this failure:

*** Assertion failure in -[UICollectionView _createPreparedSupplementaryViewForElementOfKind:atIndexPath:withLayoutAttributes:applyAttributes:], /SourceCache/UIKit/UIKit-2935.137/UICollectionView.m:1305
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UICollectionView dataSource is not set'

The solution is just override -dealloc in UICollectionViewController and release self.collectionView manually. ARC code:

- (void)dealloc {

    self.collectionView = nil;
}

Hope this will save time for somebody.

Answer 4

I was having the same issue and similarly, I was not registering the header correctly. there are several threads on here that all suggest using a Nib to define the header but I have done it differently and is working fine.

I have a custom header SizeCollectionHeader, which inherits the UICollectionReusableView. It is registered like this.

    [self.collectionView registerClass:[GRSizeCollectionHeader class] forSupplementaryViewOfKind:@"UICollectionElementKindSectionHeader"
                                                                             withReuseIdentifier:@"SupplementaryViewIdentifier"];

and is working fine.

my initial problem was that had a random "Kind" value like this.

    [self.collectionView registerClass:[GRSizeCollectionHeader class] forSupplementaryViewOfKind:@"SupplementaryViewKind"
                                                                             withReuseIdentifier:@"SupplementaryViewIdentifier"];

This will crash.

So I just wanted to comment for anybody that is looking here that you don't need to use a nib.

Answer 5

This answer is similar to the others where you create a method that checks for the data source, but it's a bit simpler. It seems the issue is related to the collection view's layout sticking around after the collection has been released. So I zeroed out the layout's properties as below and the error disappeared.

deinit {
    let layout = self.collectionView.collectionViewLayout as! UICollectionViewFlowLayout
    layout.estimatedItemSize = CGSizeZero
    layout.sectionInset = UIEdgeInsetsZero
    layout.headerReferenceSize = CGSizeZero
}

Answer 6

I kept getting the same error. I had set up the CustomHeaderView for my collectionView. I had class of the Collection Reusable View to my CustomHeaderView and i had set the identifier. I 1/2 an hour trying to figure out why this was failing.

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'could not dequeue a view of kind: UICollectionElementKindSectionFooter with identifier SectionHeader - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'

You need to read the logs carefully...lesson learned.

'could not dequeue a view of kind: UICollectionElementKindSectionFooter

The reason is because In storyboard - in the collectionView Identity Inspector I had checked both Accessories: Section Header and Section Footer. I only needed section header. Simply uncheck footer...build and run..BOOM!