Swift之三级联动UIPickerView城市选择器

初学swift语言没几天，就试着自己写了一个城市选择器，纯swift代码。

ViewController.swift文件中，个人编程习惯是把视图生命周期，视图设置，相关代理方法实现，事件响应，网络请求等方法标记后放在响应代码区，正好可以利用swift语言的extension特性将代码功能分类，这样代码不仅易读，还有利于调试：

import UIKit

//MARK: View life cycle
class ViewController: UIViewController {

    /** 懒加载的城市数据源数组 */
    fileprivate lazy var cCityDataArray:[StateModel] = {
    //Plist文件路径
    let path = Bundle.main.path(forResource: "area", ofType: "plist")
    var areas: NSArray? = nil
    //读取Plist文件数组
    if let arrayPath = path {
        areas = NSArray (contentsOfFile: arrayPath)
    }
    //数组转换为模型数组
    var cityData = Array()
    if let areasArr = areas {
        for area in areasArr {
            let areaDic = area as! NSDictionary
            let stateModel = StateModel.init(dictionary: areaDic)
            cityData.append(stateModel)
        }
    }
    return cityData
    }()
    /** 省级数据源数组 */
    fileprivate var cStatesArr: [StateModel]? = nil
    /** 市级数据源数组 */
    fileprivate var cCitiesArr: [CityModel]? = nil
    /** 区级数据源数组 */
    fileprivate var cAreasArr: [String]? = nil
    /** 选择城市的textField */
    fileprivate let cCityTextField: UITextField? = UITextField()
    /** 选择城市的pickerView */
    fileprivate let cCityPickerView: UIPickerView? = UIPickerView()
    /** 选择城市的toolBar */
    fileprivate let cCityToolBar: UIToolbar? = UIToolbar()
    /** 选择城市的背景蒙版 */
    fileprivate let cTextFieldCoverButton: UIButton = UIButton (frame: UIScreen.main.bounds)

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor(red:0.85, green:0.85, blue:0.85, alpha:1.00)
        self.setupSubviews()
        //设置数据源数组初始值
        cStatesArr = cCityDataArray
        cCitiesArr = cStatesArr?.first?.cities
        cAreasArr = cCitiesArr?.first?.areas
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

//MARK: Setup
extension ViewController {
    /** 设置subviews */
    fileprivate func setupSubviews() -> Void {
    self.setupTextField()
    self.setupCoverButton()
    self.setupPickerView()
    self.setupToolBar()
    }

    /** 设置textField */
    private func setupTextField() -> Void {
        if let cityTextField = cCityTextField {
            cityTextField.frame = CGRect (x: 50, y: 200, width: 200, height: 44)
            cityTextField.delegate = self
            cityTextField.backgroundColor = UIColor.white
            cityTextField.placeholder = "请选择城市"
            cityTextField.borderStyle = UITextBorderStyle.roundedRect
            self.view.addSubview(cityTextField)
        }
    }
    /** 设置背景蒙版Button */
    private func setupCoverButton() -> Void {
        cTextFieldCoverButton.addTarget(self, action: #selector(clickTextFieldCoverButton(sender:)), for: UIControlEvents.touchUpInside)
        self.view.addSubview(cTextFieldCoverButton)
        cTextFieldCoverButton.isHidden = true
    }

    /** 设置pickerView */
    private func setupPickerView() -> Void {
        if let cityPickerView = cCityPickerView {
            cityPickerView.delegate = self
            cityPickerView.dataSource = self
            cCityTextField!.inputView = cityPickerView
        }
    }

    /** 设置toolBar */
    private func setupToolBar() -> Void {
        if let cityToolBar = cCityToolBar {
            cityToolBar.frame = CGRect (x: 0, y: 0, width: 0, height: 44)
            cityToolBar.backgroundColor = UIColor.white
            let cancelItem = UIBarButtonItem.init(title: "取消", style: UIBarButtonItemStyle.done, target: self, action: #selector(clickToolBarCancelItem(sender:)))
            let spaceItem = UIBarButtonItem.init(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
            let doneItem = UIBarButtonItem.init(title: "确定", style: UIBarButtonItemStyle.done, target: self, action: #selector(clickToolBarDoneItem(sender:)))
            cityToolBar.items = [cancelItem, spaceItem, doneItem]
            cCityTextField?.inputAccessoryView = cityToolBar
        }
    }
}

//MARK: UITextFieldDelegate
extension ViewController: UITextFieldDelegate {

    func textFieldDidBeginEditing(_ textField: UITextField) {
        cTextFieldCoverButton.isHidden = false
    }
    
    func textFieldDidEndEditing(_ textField: UITextField) {
        cTextFieldCoverButton.isHidden = true
    }
}

//MARK: UIPickerViewDelegate
extension ViewController: UIPickerViewDelegate, UIPickerViewDataSource {
  
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 3
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        switch component {
        case 0:
            return cStatesArr!.count
        case 1:
            return cCitiesArr!.count
        case 2:
            return cAreasArr!.count
        default:
            return 0
        }
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        switch component {
        case 0:
            return cStatesArr!.count
        case 1:
            return cCitiesArr!.count
        case 2:
            return cAreasArr![row]
        default:
            return nil
        }
    }

    func pickerView(_ pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
        return self.view.frame.width / 3
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        switch component {
        case 0:
            //保存市级数据源数组
            cCitiesArr = cCityDataArray[row].cities
            //若有区级数据，则保存区级数据源数组
            if cCitiesArr?.first?.areas != nil {
                cAreasArr = cCitiesArr?.first?.areas
            }
            //重新加载第1、2组
            pickerView.reloadComponent(1)
            pickerView.reloadComponent(2)
            //默认选中第1、2组的第1行数据
            pickerView.selectRow(0, inComponent: 1, animated: true)
            pickerView.selectRow(0, inComponent: 2, animated: true)
        case 1:
            //保存区级数据源数组
            if cCitiesArr![row].areas.count != 0 {
                cAreasArr = cCitiesArr![row].areas
            }
            //重新加载第2组数据
            pickerView.reloadComponent(2)
            //默认选中第2组第1行数据
            pickerView.selectRow(0, inComponent: 2, animated: true)
        default:
            return
        }
    }
}

//MARK: Event response
extension ViewController {

    @objc fileprivate func clickTextFieldCoverButton(sender: UIButton) -> Void {
        cCityTextField?.resignFirstResponder()
    }

    @objc fileprivate func clickToolBarCancelItem(sender: UIBarButtonItem) -> Void {
        cCityTextField?.resignFirstResponder()
    }

    @objc fileprivate func clickToolBarDoneItem(sender: UIBarButtonItem) -> Void {
        cCityTextField?.resignFirstResponder()
        let selectedState = cCityPickerView?.selectedRow(inComponent: 0)
        let selectedCity = cCityPickerView?.selectedRow(inComponent: 1)
        let selectedArea = cCityPickerView?.selectedRow(inComponent: 2)
        var cityString = (cStatesArr?[selectedState!].state)! + (cCitiesArr?[selectedCity!].city)!
        if cAreasArr?.count != 0 {
            cityString += (cAreasArr?[selectedArea!])!
        }
        cCityTextField?.text = cityString
    }
}

StateModel.swift文件中，用于保存省级数据：

import UIKit

/** 省级Model */
class StateModel: NSObject {
    /** 省下级所有城市 */
    let cities: Array
    /** 省级名称 */
    let state: String
 
    init(dictionary: NSDictionary) {
        state = dictionary["state"] as! String
        let citiesArr = dictionary["cities"] as! NSArray
        var citiesMutableArr = Array()
        for city in citiesArr {
            let cityDic = city as! NSDictionary
            let cityModel = CityModel.init(dictionary: cityDic)
            citiesMutableArr.append(cityModel)
        }
        cities = citiesMutableArr
    }
}

CityModel.swift文件中，保存市/区级数据：

import UIKit

//MARK: 城市Model
class CityModel: NSObject {
    /** 城市下级area */
    let areas: Array
    /** 城市名 */
    let city: String

    init(dictionary: NSDictionary){
        city = dictionary["city"] as! String
        let areasArr = dictionary["areas"] as! NSArray
        var areasMutableArr = Array()
        for area in areasArr {
            let areaString = area as! String
            areasMutableArr.append(areaString)
        }
        areas = areasMutableArr
    }

}

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