This label seems to return nil, even though I have the reuseIdentifier and tag set properly.
override func collectionView(collectionView: UICollectionView, cell
Try removing this line from viewDidLoad:
self.collectionView!.registerClass(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
I have just created a sample project with your code and for me it works. Although you shouldn't force unwrap.
Make sure you have the correct setup in your storyboard:
Check if your collectionViewCell is setup correctly:
And set the tag of your label:
Here is the sample project