Add Items to Collection View Controller iOS Tutorial

For product name, use IOSAddItemsCollectionViewTutorial and then fill out the Organization Name and Organization Identifier with your customary values. Enter Swift as Language and choose Next.

Select The Collection View and go the Size inspector. In the Collection View section change the Cell Size to a width and height of 100 points.

Drag a Label from the Object Library and place it on the Center of the Collection View Cell.

Select the Label and go to the Attribute inspector. In the View section set the Tag value to 100.

Select the Collection View Cell and go to the Atrribute inspector. In the Collection Reusable View section set the Identifier to "Cell".

The storyboard will look like this.

Since the View Controller is removed from the Storyboard the ViewController.swift file can also be deleted from the project. Add a new file to the project, select iOS -> Source -> Cocoa Touch Class. Name it CollectionViewController and make it a subclass of UICollectionViewController.

The CollectionViewController class needs to be linked to The Collection View Controller object in the Storyboard. Select it and go the Identity Inspector. In the Custom Class section change the class to CollectionViewController

var modelData = ["Oliver","Harry","George","Jack","Noah"]

Since the Reuse Identifier is defined in the Storyboard, the following line can be removed in the CollectionViewController class

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

With the creation of the CollectionViewController class, most delegate methods are already implemented. Some methods must be tweaked a little. Change the following methods.

override func numberOfSections(in collectionView: UICollectionView) -> Int {
        // 1
        return 1
    }


    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        // 2
        return modelData.count
    }

    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
    
        // Configure the cell
        // 3
        if let label = cell.viewWithTag(100) as? UILabel {
            label.text = modelData[indexPath.row]
        }
    
        return cell
    }

Select the Assistant Editor and make sure the ViewController.swift is visible. Ctrl-click and drag from the Bar Button Item to the CollectionViewController class and create the following action

implement the addItem(_:) method

@IBAction func addItem(_ sender: Any) {
    let name = "John"
    modelData.append(name)
    let indexPath = IndexPath(row: modelData.count - 1, section: 0)
    collectionView.insertItems(at: [indexPath])
}