一个视图中有多个PickerView？

// 定义三个PickerView

var pickerView1: UIPickerView!

var pickerView2: UIPickerView!

var pickerView3: UIPickerView!

override func viewDidLoad() {

    super.viewDidLoad()

    // 初始化三个PickerView

    pickerView1 = UIPickerView(frame: CGRect(x: 0, y: 60, width: view.bounds.width, height: 160))

    pickerView2 = UIPickerView(frame: CGRect(x: 0, y: 220, width: view.bounds.width, height: 160))

    pickerView3 = UIPickerView(frame: CGRect(x: 0, y: 380, width: view.bounds.width, height: 160))

    // 设置数据源和代理

    pickerView1.dataSource = self

    pickerView1.delegate = self

    pickerView2.dataSource = self

    pickerView2.delegate = self

    pickerView3.dataSource = self

    pickerView3.delegate = self

    // 添加到视图中

    view.addSubview(pickerView1)

    view.addSubview(pickerView2)

    view.addSubview(pickerView3)

}

// 返回选项个数

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

    return 1

}

// 返回每个选项的行数

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {

    if pickerView == self.pickerView1 {

        return 10 // 第一个PickerView有10个选项

    } else if pickerView == self.pickerView2 {

        return 20 // 第二个PickerView有20个选项

    } else {

        return 30 // 第三个PickerView有30个选项

    }

}

// 返回每个选项的标题

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {

    if pickerView == self.pickerView1 {

        return "\(row)" // 第一个PickerView的选项为数字

    } else if pickerView == self.pickerView2 {

        return "\(row)" // 第二个PickerView的选项为数字

    } else {

        return "\(row)" // 第三个PickerView的