UICollectionView wrapped in a UIViewController

Question

I have a UICollectionView that I placed in a custom UIViewController via Storyboard and pinned its leading/trailing/top/bottom space to its superview.

Then I have a custom UICollectionViewController subclass that should use the collection view. So in the superview's UIViewController (PrimaryViewController) I have an outlet to the collection view and I instantiate my custom UICollectionViewController. I assign it the collection view and I assign the custom UICollectionViewController as delegate and dataSource for the collection view.

But when I run this, the collection view doesn't appear on the screen. It is obvious that the viewDidLoad() doesn't get called in the custom UICollectionViewController class so either I'm missing a key part or I'm approaching this the wrong way.

Can somebody tell me how to construct the connection between the collection view (which is placed via Storyboard) and the custom UICollectionViewController class (which is code only) in a way that makes this work properly?

Here's my (simplified) code so far ...

class PrimaryViewController : UIViewController {
    @IBOutlet private weak var _collectionView:UICollectionView!
    private var _collectionViewCtrl:CustomCollectionViewController!

    override func viewDidLoad() {
        super.viewDidLoad()
        _collectionViewCtrl = CustomCollectionViewController(collectionView: _collectionView)
    }
}


class CustomCollectionViewController : UICollectionViewController {
    init(collectionView:UICollectionView) {
        super.init(nibName: nil, bundle: nil)

        self.collectionView = collectionView
        self.collectionView.delegate = self
        self.collectionView.dataSource = self
    }

    required init(coder aDecoder:NSCoder) {
        super.init(coder: aDecoder)
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

Why not embed the CustomCollectionViewController in the PrimaryViewController IB. You can add a UICollectionViewController to the UIViewController and then change it's class to your custom class. — thelaws
@thelaws The reason for this is that there is also a toolbar in my PrimaryViewController's view, not only the collection view alone. — BadmintonCat

HighFlyingFantasy HighFlyingFantasy · Accepted Answer · 2014-09-02T18:19:25

In IB or your Storyboard, you can use a container view and embed your custom collection view controller inside. This gives you the ability to manipulate each view controller in it's own context, because they each have their own nib, and will handle instantiating your collection view controller auto-magically.

Your PrimaryViewController can look like this:

class PrimaryViewController : UIViewController {
    @IBOutlet private weak _collectionView: UIView
    private var _collectionViewController: CustomCollectionViewController! {
        // ???: You can also iterate through child view controllers looking for a class match if you embed other controllers.
        return self.childViewControllers[0] as CustomCollectionViewController!
    }

    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

Which will also call viewDidLoad() on your CustomCollectionViewController. You can hide and show the view through the _collectionView property, or directly manipulate it through _collectionViewController.

The pain comes from any logic that may be the appearance logic (viewWillAppear(_: Bool), viewWillDisappear(_: Bool), etc) because you'll have to trigger those yourself.

Your storyboard should look something like this (My container view is hidden):

Storyboard example

UICollectionView wrapped in a UIViewController

2 Answers