You have to get the frame of the tapped collectionViewItem. This is done like follows
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewLayoutAttributes *attributes = [collectionView layoutAttributesForItemAtIndexPath:indexPath];
CGRect cellRect = [attributes frame];
}
Then you initiate your viewcontroller, set its frame to the frame of the cell and then use -animateWithDuration:completion:
to make the animation.
I actually did that even in iOS6.
I hope that helps.