Question

I have a view set up with two UICollectionViews. Each of these views has an array backing it with different sizes. collection1 is backed by array1, and collection2 is backed by array2. The problem is, what ever number is returned for collection1 from numberOfItemsInSection is being applied to both collection views.

For instance, if array1 is size 4 and array2 is size 5, both collections will show 4 elements. If array1 is size 5 and array2 is size 4, when I scroll collection2 all the way it calls cellForItemAtIndexPath with an itemIndex of 5 for collection2 and I get an NSRangeException.

How can I make each collectionView use it’s own size?

- (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:(NSInteger)section;
{
    if(view == self.colleciton1){
        return self.array1.count;
    } else if (view == self.collection2){
        return self.array2.count;
    }

    return 0;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)cv cellForItemAtIndexPath:(NSIndexPath *)indexPath;
{
    if(cv == self.collection1){
        CharacterCell *cell = [cv dequeueReusableCellWithReuseIdentifier:FIRST_CELL_IDENTIFIER forIndexPath:indexPath];
        cell.label.text = self.array1[indexPath.item];
        return cell;
    } else if (cv == self.collection2){
        EpisodeCell *cell = [cv dequeueReusableCellWithReuseIdentifier:SECOND_CELL_IDENTIFIER forIndexPath:indexPath];
        cell.label.text = self.array2[indexPath.item];
        return cell;
    }

    return nil;
}

I’ve included a git repo with a project illustrating the problem.

[e-mail]:civatrix/MultipleCollectionViews.git

Answer 1

The problem was that I was using the same layout object for each collection. In retrospect that makes sense, but you have to make sure you create different layouts for each collectionView.