How to add UICollectionView to the inputAccessoryView

I want to add UICollectionView to the inputAccessoryView so that I can scroll the list.

override var inputAccessoryView: UIView? {
    let customView = UIView(frame: CGRect(x: 0, y: 0, width: 10, height: 80))
    customView.backgroundColor = UIColor.red
    return customView
}

To add a UICollectionView as inputAccessoryView,

1. Create a custom UIView containing a UICollectionView first and add the UICollectionViewDataSource methods to it.

class CustomView: UIView, UICollectionViewDataSource {
    @IBOutlet weak var collectionView: UICollectionView!

    let words = ["abscind","downwind","headwind","lind","rescind","sind","skinned","tailwind","thin-skinned","tinned","twinned","upwind","whirlwind","wind"]

    override func awakeFromNib() {
        super.awakeFromNib()
        self.collectionView.register(UINib(nibName: "CustomCell", bundle: nil), forCellWithReuseIdentifier: "cell")
    }

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return self.words.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CustomCell
        cell.label.text = self.words[indexPath.row]
        return cell
    }
}

class CustomCell: UICollectionViewCell {
    @IBOutlet weak var label: UILabel!
}

2. Add the instance of above created CustomView as the inputAccessoryView of UITextField/UITextView as per your requirement.

class ViewController: UIViewController {
    @IBOutlet weak var textField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        if let customView = Bundle.main.loadNibNamed("CustomView", owner: self, options: nil)?.first as? CustomView {
            self.textField.inputAccessoryView = customView
        }
    }
}

In the above code, you can configure the collectionView with data as required.