How to implement simple Collection View using storyboard in Swift5

[Step 1] : Add collectionView in your storyboard (Main.storyboard) or custom storyboard.

[Step 2] : Declare and link your collectionView in class ViewController or your custom class.

@IBOutlet weak var collectionView: UICollectionView!
private let cellId = "cellId"

[Step 3] : Add inherit UICollectionViewDataSource & (using extension)

extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath)
cell.backgroundColor = .red
return cell
}
}

[Step 4] : Add inherit UICollectionViewDelegate

extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print(indexPath.item)
}
}

[Step 5] : Declare delegate, datasource = self & register collectionViewCell in class ViewController

override func viewDidLoad() {
super.viewDidLoad()
collectionView.delegate = self
collectionView.dataSource = self
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: cellId)
}

[Step 6] : Add inherit UICollectionViewDelegateFlowLayout for adjusting size of cell.

extension ViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: 200)
}
}

Result: