1つのVCで2つのPickerを使いたい

前提・実現したいこと

1つの__UIViewController__に2つの__UIPickerView__を使いたい．

該当のソースコード

Swift
1import UIKit
2
3class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
4    
5    @IBOutlet weak var xPicker: UIPickerView!
6    @IBOutlet weak var yPicker: UIPickerView!
7
8    xArray = ["a", "b", "c"]
9    yArray = ["A", "B", "C"]
10
11    override func viewDidLoad() {
12        super.viewDidLoad()
13        
14        xPicker.delegate = self
15        xPicker.dataSource = self
16        yPicker.delegate = self
17        yPicker.dataSource = self
18    }
19    
20    
21    func numberOfComponents(in pickerView: UIPickerView) -> Int {
22        return 1
23    }
24    
25
26    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
27        if pickerView is xPicker {  //ここの行でエラー
28            return xArray.count
29        } else {
30            return yArray.count
31        }
32    }
33
34
35    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
36        if pickerView is xPicker {  //ここの行でエラー
37            return xArray[row]
38        } else {
39            return yArray[row]
40        }
41    }
42}