ios - 使用两个 UIPickerView 时出现问题 - 第一个世界，第二个世界没有

Question

我尝试在两个不同的文本框上使用两个选择器 View (我将它们对齐在文本框下方并隐藏它们直到被调用)。我隐藏选取器 View ，直到准备好使用并将两个文本框绑定(bind)到相应的文本框。第一个选择器 View 工作正常，但是当我单击第二个选择器 View 时，我的列表没有出现，并且它似乎仍然隐藏。我已经多次阅读代码，但找不到问题，并且观看了多个视频并检查了苹果文档，但无济于事。下面发布了代码以供审核和帮助。提前致谢!

class fifthViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource, UITextFieldDelegate {

    @IBOutlet weak var heightInput: UITextField!
    @IBOutlet weak var weightInput: UITextField!
    @IBOutlet weak var bmiOutput: UITextField!
    @IBOutlet weak var weightPicker: UIPickerView!
    @IBOutlet weak var heightPicker: UIPickerView!

    var height = ["48", "49", "50"]
    var weight = ["90", "91", "92"]

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

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        var countrows : Int = height.count
        if pickerView == weightPicker {
        countrows = self.weight.count
        }
        return countrows
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if pickerView == heightPicker {
        let titleRow = height[row]
            return titleRow
        }
        else if pickerView == weightPicker {
            let titleRow = weight[row]
            return titleRow
        }
        return ""
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        if pickerView == heightPicker {
            self.heightInput.text = self.height[row]
            self.heightPicker.isHidden = true
        }
        else if pickerView == weightPicker {
            self.weightInput.text = self.weight[row]
            self.weightPicker.isHidden = true
        }
    }

    func textFieldDidBeginEditing(_ textField: UITextField) {
        if (textField == self.heightInput) {
            self.heightPicker.isHidden = false
        }
        else if (textField == self.weightInput) {
            self.weightInput.isHidden = false
        }
    }```

Answer 1

在textFieldDidBeginEditing()中，您需要将self.weightPicker.isHidden设置为false而不是self.weightInput.isHidden .

func textFieldDidBeginEditing(_ textField: UITextField) {
    if (textField == self.heightInput) {
        self.heightPicker.isHidden = false
    }
    else if (textField == self.weightInput) {
        self.weightPicker.isHidden = false
    }
}

<小时/>

修改代码以使用 inputViews

我同意@PaulW11的评论:

"You would be almost certainly better off if you made the picker views the inputView of each text field."

以下是基本设置所需的更改。删除 Storyboard 中的选择器并断开 @IBOutlet 连接。

然后添加这些修改:

// These are no longer outlets since they're created in code
var weightPicker: UIPickerView!
var heightPicker: UIPickerView!

override func viewDidLoad() {
    super.viewDidLoad()

    // set up the picker views
    self.weightPicker = UIPickerView()
    self.weightPicker.delegate = self
    self.weightPicker.dataSource = self

    self.heightPicker = UIPickerView()
    self.heightPicker.delegate = self
    self.heightPicker.dataSource = self

    self.heightInput.inputView = self.heightPicker
    self.weightInput.inputView = self.weightPicker
}

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if pickerView == heightPicker {
        self.heightInput.text = self.height[row]

        // make picker go away after value has been selected
        self.heightInput.resignFirstResponder()
    }
    else if pickerView == weightPicker {
        self.weightInput.text = self.weight[row]

        // make picker go away after value has been selected
        self.weightInput.resignFirstResponder()
    }
}