自定义带有确定按钮的 UIPickerView

自定义 UIPickerView：

import Foundation
import UIKit

protocol ToolbarPickerViewDelegate: class {
    func didTapDone()
    func didTapCancel()
}

class ToolbarPickerView: UIPickerView {

    public private(set) var toolbar: UIToolbar?
    public weak var toolbarDelegate: ToolbarPickerViewDelegate?

    override init(frame: CGRect) {
        super.init(frame: frame)
        self.commonInit()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.commonInit()
    }

    private func commonInit() {
        let toolBar = UIToolbar()
        toolBar.barStyle = UIBarStyle.default
        toolBar.isTranslucent = true
        toolBar.tintColor = .black
        toolBar.sizeToFit()

        let doneButton = UIBarButtonItem(title: "确定", style: .plain, target: self, action: #selector(self.doneTapped))
        let spaceButton = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
        let cancelButton = UIBarButtonItem(title: "取消", style: .plain, target: self, action: #selector(self.cancelTapped))

        toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)
        toolBar.isUserInteractionEnabled = true

        self.toolbar = toolBar
    }

    @objc func doneTapped() {
        self.toolbarDelegate?.didTapDone()
    }

    @objc func cancelTapped() {
        self.toolbarDelegate?.didTapCancel()
    }
}

实用方法：

class MyViewController: UIViewController {

    @IBOutlet weak var textField: UITextField!
    fileprivate let pickerView = ToolbarPickerView()
    fileprivate let titles = ["0", "1", "2", "3"]

    override func viewDidLoad() {
        super.viewDidLoad()

        self.textField.inputView = self.pickerView
        self.textField.inputAccessoryView = self.pickerView.toolbar

        self.pickerView.dataSource = self
        self.pickerView.delegate = self
        self.pickerView.toolbarDelegate = self

        self.pickerView.reloadAllComponents()
    }
}

extension MyViewController: UIPickerViewDataSource, UIPickerViewDelegate {

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

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

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

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        self.textField.text = self.titles[row]
    }
}

extension MyViewController: ToolbarPickerViewDelegate {

    func didTapDone() {
        let row = self.pickerView.selectedRow(inComponent: 0)
        self.pickerView.selectRow(row, inComponent: 0, animated: false)
        self.textView.text = self.titles[row]
        self.textField.resignFirstResponder()
    }

    func didTapCancel() {
        self.textField.text = nil
        self.textField.resignFirstResponder()
    }
}