CODEWITHSUNDEEP
iosswiftswift3swift2uicollectionview
Tushar Sharma
Tushar Sharma

Reputation: 2882

UICollectionView Programmatically

I created my own window in storyboard like below:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.makeKeyAndVisible()
        window?.rootViewController = UINavigationController(rootViewController: HomeController())
        return true
    }

This actually worked fine when my class is subclassing UIViewController.

class HomeController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        view.backgroundColor = UIColor.red
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

Now when I subclass my class with UICollectionViewController:

class HomeController: UICollectionViewController {

        override func viewDidLoad() {
            super.viewDidLoad()
            // Do any additional setup after loading the view, typically from a nib.
            Collectionview.backgroundColor = UIColor.red
        }

        override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
            // Dispose of any resources that can be recreated.
        }


    }

At runtime it gives me an error saying:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'UICollectionView must be initialized with a non-nil layout parameter' *** First throw call stack:

In my understanding it is asking me to give layout for UICollectionView.Correct me here if I am wrong.So I tried this-:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.makeKeyAndVisible()
        let layout = UICollectionViewFlowLayout()
        window?.rootViewController = UINavigationController(rootViewController: HomeController(UICollectionViewLayout: layout))
        return true
    }

But Still ending up with an error:

Argument labels 'UICollectionViewLayout' do not match any available overloads.

Am I using a wrong swift3 syntax? If yes what is correct to solve out this issue.

Upvotes: 0

Views: 4331

Answers (2)

Vishal Singh
Vishal Singh

Reputation: 4480

You need to use UICollectionViewController's designated intialiser as below.

let layout = UICollectionViewLayout()
let homeViewController = HomeController(collectionViewLayout: layout)
window?.rootViewController = UINavigationController(rootViewController: homeViewController)

Along with that, you will need to modify you HomeViewController to implement UICollectionViewDataSource required methods.

override func viewDidLoad() {
        super.viewDidLoad()

        // Uncomment the following line to preserve selection between presentations
        // self.clearsSelectionOnViewWillAppear = false

        // Register cell classes
        self.collectionView!.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "Cell")

        // Do any additional setup after loading the view.
    }


// MARK: UICollectionViewDataSource

    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        // #warning Incomplete implementation, return the number of sections
        return 0
    }


    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // #warning Incomplete implementation, return the number of items
        return 0
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)

        // Configure the cell

        return cell
    }

Upvotes: 2

Mahendra
Mahendra

Reputation: 8904

You need to implement UICollectionViewFlowLayout in UICollectionViewController.

Check this Link

You must use initWithFrame:collectionViewLayout: to initialise your UICollectionView and you must pass a non-nil UICollectionViewLayout object.

Upvotes: 1

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