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

I also got this annoying error:

*** Assertion failure in -[UICollectionView _createPreparedSupplementaryViewForElementOfKind:atIndexPath:withLayoutAttributes:applyAttributes:], /SourceCache/UIKit/UIKit-3347.44/UICollectionView.m:1400
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UICollectionView dataSource is not set'

and I found some people solving this error by doing

- (void)dealloc {
    self.collectionView = nil;
}

or in swift:

deinit {
    collectionView = nil
}

however neither of these solved my crash. I tried a few things out and the following "hack" solved this annoying bug:

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
    if collectionView.dataSource != nil {
        return someHeaderSize
    } else {
        return CGSizeZero
    }
}

Answer 2

The answers in this topic are quite old, and do not work in iOS8 and iOS9. If you are still having the described issue, check out the following topic: UICollectionView and Supplementary View crash

EDIT:

Here is the answer, in case the link becomes invalid:

If you are using custom layout in your collection view, check if its datasource is nil in:

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect

The result should look something like this:

- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
    if (self.collectionView.dataSource != nil) {
        // Your layout code    
        return array;
    }
    return nil;
}

This change resolves the following issue:

• Assertion failure in -[UICollectionView _createPreparedSupplementaryViewForElementOfKind:atIndexPath:withLayoutAttributes:applyAttributes:]

You can also check the following topic, however it didn't resolve anything in my case:

Removing empty space, if the section header is hidden in the UICollectionView

Hope it will help you, and you won't waste as much time as I did.

Answer 3

Try this :

self.collectionView?.dataSource = nil
self.collectionView = nil

It worked for me ;)

Answer 4

A iOS9 bug, In viewcontroller's dealloc set layer delegate nil.

- (void)dealloc{

    if ([[[UIDevice currentDevice] systemVersion] hasPrefix:@"9"]) {
        self.collectionView.layer.delegate = nil;
    }
}