Ios PickerView中的内容未显示

我是Swift编程新手。当我想用2个不同的内容显示2个不同的选择器时，我遇到了问题。但它显示（？）而不是内容

请看下面的截图

谢谢你的帮助

let fruit = ["apple", "orange", "watermelon", "banana", "peach", "strawberry"]
let food = ["rice","bread","spagheti","milk"]


func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    if (pickerView.tag == 1) {
        return fruit.count
    }
    else {
        return food.count
    }
}    

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    if (pickerView.tag == 1) {
        return fruit[row]
    }
    else {
        return food[row]
    }
}

---

首先检查pickerView

DataSource

和

Delegate

是否连接正确，然后通过比较pickerView有条件地加载数据，如下所示

func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 1
}

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    if pickerView == YOUR_FIRST_PICKER {
        return fruit.count
    }
    else {
        return food.count
    }
}    

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    if pickerView == YOUR_FIRST_PICKER {
        return fruit[row]
    }
    else {
        return food[row]
    }
}

---

我认为您还没有设置选择器的委托和数据源

首先将这些协议添加到ViewController子类中

class ViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource

然后在

viewDidLoad

中，将选取者的委托和数据源设置为

self

override func viewDidLoad() {
    super.viewDidLoad()
    pickerView1.delegate = self
    pickerView1.dataSource = self
    pickerView2.delegate = self
    pickerView2.dataSource = self
}

---

确保您设置了

datasource

和

delegate

我已经设置好了。@fnsmp，您在评论中明确提到您已经将

delegate

和

datasource

设置到您的PickerView，那么您怎么能接受这个答案呢？