PickerTextField for medium post

PickerTextField.swift

import SwiftUI

class PickerTextField: UITextField {
    // MARK: - Public properties
    var data: [String]
    @Binding var selectionIndex: Int?

    // MARK: - Initializers
    init(data: [String], selectionIndex: Binding<Int?>) {
        self.data = data
        self._selectionIndex = selectionIndex
        super.init(frame: .zero)

        self.inputView = pickerView
        self.inputAccessoryView = toolbar
        self.tintColor = .clear

        guard let selectionIndex = selectionIndex.wrappedValue else {
            return
        }

        self.pickerView.selectRow(selectionIndex, inComponent: 0, animated: true)
    }

    @available(*, unavailable)
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    // MARK: - Private properties
    private lazy var pickerView: UIPickerView = {
        let pickerView = UIPickerView()
        pickerView.delegate = self
        pickerView.dataSource = self
        return pickerView
    }()

    private lazy var toolbar: UIToolbar = {
        let toolbar = UIToolbar()

        let flexibleSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)

        let doneButton = UIBarButtonItem(
            title: "Done",
            style: .done,
            target: self,
            action: #selector(donePressed)
        )

        toolbar.setItems([flexibleSpace, doneButton], animated: false)
        toolbar.sizeToFit()
        return toolbar
    }()

    // MARK: - Private methods
    @objc
    private func donePressed() {
        self.selectionIndex = self.pickerView.selectedRow(inComponent: 0)
        self.endEditing(true)
    }
}

// MARK: - UIPickerViewDataSource & UIPickerViewDelegate extension
extension PickerTextField: UIPickerViewDataSource, UIPickerViewDelegate {
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return self.data.count
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return self.data[row]
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        self.selectionIndex = row
    }
}