实现日期年月日的三级联动选择，可以创建一个包含三个列的UIPickerView。每个列分别表示年、月、日。根据用户的选择来动态更新每个列的数据。
首先，我们需要创建一个UIViewController，并在其上添加一个UIPickerView。然后，为每个列设置数据源和代理方法。
下面是一个简单的实现代码示例：
import UIKitclass ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {@IBOutlet weak var pickerView: UIPickerView!let years = Array(1970...2021)let months = Array(1...12)let days = Array(1...31)override func viewDidLoad() {super.viewDidLoad()pickerView.dataSource = selfpickerView.delegate = self}// MARK: - UIPickerViewDataSourcefunc numberOfComponents(in pickerView: UIPickerView) -> Int {return 3}func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {if component == 0 {return years.count} else if component == 1 {return months.count} else {return days.count}}// MARK: - UIPickerViewDelegatefunc pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {if component == 0 {return String(years[row])} else if component == 1 {return String(months[row])} else {return String(days[row])}}func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {let selectedYear = pickerView.selectedRow(inComponent: 0)let selectedMonth = pickerView.selectedRow(inComponent: 1)let selectedDay = pickerView.selectedRow(inComponent: 2)let year = years[selectedYear]let month = months[selectedMonth]let day = days[selectedDay]print("Selected date: \(year)-\(month)-\(day)")}}这个示例中，我们创建了一个包含三个列的UIPickerView。每个列分别显示年、月和日的数据。用户选择日期时，我们通过UIPickerViewDelegate方法来获取所选值，并打印出来。
请注意，这只是一个简单的示例，你可以根据需要自定义UIPickerView的外观和行为。
