Show UIPickerView like a keyboard, without UITextField

Question

I\'m looking for a way to present a UIPickerView when the user taps on a UIBarButtonItem. Imagine a filter for the table view results.

I know I

Answer 1

Based on borisgolovnev's suggestion and CodeMonkey's answer, I have implemented the idea with an invisible UITextField in the following way in Swift 5.

import UIKit

class PickerViewPresenter: UITextField, UIPickerViewDataSource, UIPickerViewDelegate {
    private lazy var doneToolbar: UIToolbar = {
        let toolbar = UIToolbar(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 50))

        let flexSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
        let doneButton = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(doneButtonTapped))

        let items = [flexSpace, doneButton]
        toolbar.items = items
        toolbar.sizeToFit()

        return toolbar
    }()

    private lazy var pickerView: UIPickerView = {
        let pickerView = UIPickerView()
        pickerView.dataSource = self
        pickerView.delegate = self
        return pickerView
    }()

    var items: [Item] = []
    var didSelectItem: ((Item) -> Void)?

    private var selectedItem: Item?

    init() {
        super.init(frame: .zero)
        setupView()
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    private func setupView() {
        inputView = pickerView
        inputAccessoryView = doneToolbar
    }

    @objc private func doneButtonTapped() {
        if let selectedItem = selectedItem {
            didSelectItem?(selectedItem)
        }
        resignFirstResponder()
    }

    func showPicker() {
        becomeFirstResponder()
    }

    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1
    }

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

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

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        selectedItem = items[row]
    }
}

Usage in your ViewController:

private var selectedItem: Item?

private lazy var pickerViewPresenter: PickerViewPresenter = {
    let pickerViewPresenter = PickerViewPresenter()
    pickerViewPresenter.didSelectItem = { [weak self] item in
        self?.selectedItem = item
    }
    return pickerViewPresenter
}()

view.addSubview(pickerViewPresenter)

// e.g. on a button tap
@objc private func buttonTapped() {
    pickerViewPresenter.showPicker()
}

Example:

I have attached it to a UITapGestureRecognizer.