UICollectionView Footers. Read the docs, still can't get one to show. Must be done programmatically

Question

I'm trying to add supplemental footers into a UICollectionView. It seems like I'm hitting all the proper methods according to Apple's documentation but for some reason the:

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

...isn't getting called at all.

I've subclassed UICollectionReusableView to a class called SmartActionFooterView.

In the ViewController, in the ViewDidLoad method I'm registering and associating views with reuse identifier as such:

    [self.collectionView registerClass:[SmartActionFooterView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footerView"];

And then overriding the UICollectionFlowDelegate method with...

- (CGSize)collectionView:(UICollectionView *)collectionView
                  layout:(UICollectionViewLayout *)collectionViewLayout
 referenceSizeForFooterInSection:(NSInteger)section
{
    NSLog(@"sizing footer");
    return CGSizeMake(300,100);
}

This NSLog is printing out.

I'm then hitting the UICollectionViewDataSource method...

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{

NSLog(@"Something is happening with the footer...");
SmartActionFooterView *footerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footerView" forIndexPath:indexPath];

footerView.backgroundColor = [UIColor yellowColor];

return footerView;
}

This NSLog however is printing nothing, however I'm at a loss as to why.

I have the constraint of needing to do this all programmatically (no storyboards).

Thanks!

Answer 1

I advice you to debug and check. Debugging is a very powerful tool in any IDE and it helps most of the times.
What I think you have not done is to set the datasource and delegate properties of your UICollectionView object.

So, try:

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

Answer 2

Found the problem.

I was subclassing UICollectionViewFlowLayout and incorrectly calling:

layoutAttributesForSupplementaryViewOfKind:atIndexPath

properly in said subclass. The call for this method needed to be done in the:

layoutAttributesForElementsInRect:

and the attributes then passed into a mutable array.

From my understanding of the documents here. The even though the method for creating and dequeueing footers in my View Controller is part of the UICollectionViewDataSource protocol, the datasource first checks with the UICollectionViewFlowLayout to see what objects need to be created.