转载请声明出处：http://blog.csdn.net/jinnchang/article/details/44487269

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1、Summary

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2、Code

//
//  ViewController.swift
//  UIPickerViewSample
//
//  Created by jinnchang on 15/3/18.
//  Copyright (c) 2015年 Jinn Chang. All rights reserved.
//

import UIKit

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {

    var myPickerView: UIPickerView?

    var provinces = [String: [String]]()
    var cities = [String]()

    override func viewDidLoad() {

        // 载入数据
        provinces = ["浙江省":["杭州市","宁波市"],"安徽省":["黄山市","合肥市"]]
        cities = provinces.values.array[0]

        // 定义一个按钮，使数据回到默认状态
        let button1 = UIButton.buttonWithType(.System) as? UIButton
        button1?.frame = CGRectMake(self.view.frame.width/2 - 200, 50, 400, 50)
        button1?.setTitle("回到默认状态", forState: UIControlState.Normal)
        button1?.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
        button1?.tag = 1

        // 定义一个按钮，刷新所有数据
        let button2 = UIButton.buttonWithType(.System) as? UIButton
        button2?.frame = CGRectMake(self.view.frame.width/2 - 200, 150, 400, 50)
        button2?.setTitle("刷新所有元素", forState: UIControlState.Normal)
        button2?.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
        button2?.tag = 2

        // 定义一个按钮，显示当前选中的省市
        let button3 = UIButton.buttonWithType(.System) as? UIButton
        button3?.frame = CGRectMake(self.view.frame.width/2 - 200, 250, 400, 50)
        button3?.setTitle("显示当前选中省市", forState: UIControlState.Normal)
        button3?.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside)
        button3?.tag = 3

        // 初始化 myPickerView
        myPickerView = UIPickerView(frame: CGRectMake(0, self.view.frame.height - 200, self.view.frame.width, 200))
        myPickerView?.delegate = self
        myPickerView?.dataSource = self
        // 显示选中框，iOS7 以后不起作用
        myPickerView?.showsSelectionIndicator = false

        self.view.addSubview(button1!)
        self.view.addSubview(button2!)
        self.view.addSubview(button3!)
        self.view.addSubview(myPickerView!)
    }

    // 设置列数
    func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
        return 2
    }

    // 设置行数
    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        if(component == 0){
            return provinces.keys.array.count
        }
        if(component == 1){
            return provinces.count
        }
        return 0
    }

    // 设置每行具体内容（titleForRow 和 viewForRow 二者实现其一即可）
    func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
        if(component == 0){
            return provinces.keys.array[row]
        }
        if(component == 1){
            return cities[row]
        }
        return nil
    }

    // 选中行的操作
    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if(component == 0){
            cities = provinces[provinces.keys.array[row]]!
            // 重新加载二级选项并复位
            myPickerView?.reloadComponent(1)
            myPickerView?.selectRow(0, inComponent: 1, animated: true)
        }
    }

    /// 响应按钮点击事件
    func buttonAction(sender: UIButton) {
        let num = sender.tag
        switch num {
        case 1:
            // 复原数据并重置
            provinces = ["浙江省":["杭州市","宁波市"],"安徽省":["黄山市","合肥市"]]
            cities = provinces.values.array[0]
            myPickerView?.reloadAllComponents()
            myPickerView?.selectRow(0, inComponent: 0, animated: true)
            myPickerView?.selectRow(0, inComponent: 1, animated: true)
        case 2:
            // 载入新数据并重置
            provinces = ["浙江":["杭州","宁波"],"安徽":["黄山","合肥"]]
            cities = provinces.values.array[0]
            myPickerView?.reloadAllComponents()
            myPickerView?.selectRow(0, inComponent: 0, animated: true)
            myPickerView?.selectRow(0, inComponent: 1, animated: true)
        case 3:
            // 显示当前选中的省市
            let provinceNum = myPickerView?.selectedRowInComponent(0)
            let cityNum = myPickerView?.selectedRowInComponent(1)
            println("province:\(provinces.keys.array[provinceNum!]);city:\(cities[cityNum!])")
        default:
            break
        }
    }

}

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3、Resource

Github 上项目地址：UIPickerViewSample

文章最后更新时间：。参考资料如下：

UIPickerView Class Reference

UIKit
User Interface Catalog: Picker Views