I have created a custom UICollectionViewCell in Interface Builder, binded views on it to the class, and then when I want to use and set a string to the label on the string,
I think that best solution is to directly use from storyboard where add a CollectionView, in alternative you need to remove a CollectionViewCell from your CollectionView in storyboard and register a cell with the following command:
collectionView?.register(UINib(nibName: "YourItemClassName", bundle: nil), forCellWithReuseIdentifier: "yourIdentifier")