Remove selected IndexPath before notifying delegate

[michaelzoech]

The contract for deselectItemAtIndexPath is to remove the index path
from the array before notifying the delegate. This allows the user
to check the selectedIndexes if there are remaining selections.

This patch applies this contract to reloadData where until now
selectedIndexes was cleaned after notifying the delegate.

[jwilling]

Thank you for putting this together! ✨

I'm debating whether this is the behavior that would be desired, however. Would it make more sense to remove all selected indexes first, then notify the delegate? That way when the delegate receives each message the state would be finalized. Here's what I'm thinking:

- (void)reloadData {
    _collectionViewFlags.wantsLayout = YES;

    NSArray *selectedIndexes = self.selectedIndexes.copy;   
    [self.selectedIndexes removeAllObjects];

    // Remove any selected indexes we've been tracking.
    if (_collectionViewFlags.delegateDidDeselect) {
        for (NSIndexPath *indexPath in selectedIndexes) {
            [self.delegate collectionView:self didDeselectItemAtIndexPath:indexPath];
        }
    }

    // ...
}

What do you think?

[michaelzoech]

Sounds good to me. I've updated the PR

[jwilling]

Thanks again! 🌴

[michaelzoech]

np. thx for providing such an awesome library.