Pickerview 在文本字段中第二次单击时显示为空，当我按下完成或取消应用程序崩溃时

Posted 2023-02-24

【中文标题】Pickerview 在文本字段中第二次单击时显示为空，当我按下完成或取消应用程序崩溃时

【英文标题】：Pickerview is showing empty on second click in the textfield, adn when i press Done or Cancel the App crashes

【发布时间】：2020-07-16 12:30:54

【问题描述】：

var gender = ["MALE","FEMALE", "Other"]
var genderPicker: UIPickerView! = UIPickerView()

// 在文本字段中第一次单击时，性别选择器视图工作正常，但如果我按下然后在性别文本字段中再次按下，选择器显示为空。

// 当我按下取消或完成关闭选择器时，应用程序崩溃并出现以下错误

将无法识别的选择器发送到实例”在 swift 中

override func viewDidLoad() 
    super.viewDidLoad()
    tableViewHeight.constant = screenHeight * 0.7
    // Do any additional setup after loading the view.
    let toolBar = UIToolbar()
    toolBar.barStyle = UIBarStyle.default
    toolBar.isTranslucent = true
    toolBar.tintColor = UIColor.systemBlue
    toolBar.sizeToFit()

    let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItem.Style.plain, target: self, action: "donePicker")
    let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace, target: nil, action: nil)
    let cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItem.Style.plain, target: self, action: "donePicker")
    
    toolBar.setItems([cancelButton, spaceButton, doneButton], animated: false)
    toolBar.isUserInteractionEnabled = true
    
    genderTxtField.delegate = self
    genderPicker!.delegate = self
    genderPicker!.dataSource = self
    genderTxtField.inputAccessoryView = toolBar
    self.genderTxtField.inputView = genderPicker
    


func donePicker() 
    genderTxtField.resignFirstResponder()

// 委托方法

extension InsuranceMethodsSemiViewController: UITextFieldDelegate 
    func textFieldShouldBeginEditing(textField: UITextField) -> Bool 
        genderPicker.isHidden = false
        genderTxtField.inputView = genderPicker;
        return false
    
    func textFieldDidEndEditing(_ textField: UITextField) 
        genderPicker.isHidden = true
    


extension InsuranceMethodsSemiViewController: UIPickerViewDelegate 
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? 
        return gender[row]
    

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
    genderTxtField.text = gender[row]
    self.view.endEditing(true)
    pickerView.isHidden = true



extension InsuranceMethodsSemiViewController: UIPickerViewDataSource 
    func numberOfComponents(in pickerView: UIPickerView) -> Int 
        return 1
    

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
        return gender.count
    

【参考方案1】：

1- 添加_

func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool 
    genderPicker.isHidden = false
    genderTxtField.inputView = genderPicker;
    return true

2- 将操作更改为#selector(donePicker)

let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItem.Style.plain, target: self, action: #selector(donePicker))
let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.flexibleSpace, target: nil, action: nil)
let cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItem.Style.plain, target: self, action: #selector(donePicker))

有

@objc func donePicker() 

【讨论】：

好吧，如果我从选择器中选择一个输入，比如女性，文本字段会接受输入，但是当我再次按下时，选择器显示为空，知道修改解决了所有其他问题 :)

我没有注意到我应该添加 _ 但是当我添加它时，文本字段停止响应

让它return true