在“UIPickerView”功能设置上接收错误

Posted 2023-02-24

【中文标题】在“UIPickerView”功能设置上接收错误

【英文标题】：Receiving errors on 'UIPickerView' func settings

【发布时间】：2018-06-04 16:57:09

【问题描述】：

我在一个应用程序中有两个（或更多）文本字段，我希望每个文本字段在被选中时弹出自己的 Pickerview 轮...这是我目前所得到的：

var pickerView = UIPickerView()

@IBOutlet weak var serviceType: UITextField!
@IBOutlet weak var brandsField: UITextField!

var serviceArray = ["Services", "..."]
var brandsArray = ["Apple", "Samsung"]

override func viewDidLoad() 
    super.viewDidLoad()

    pickerView.delegate = self
    pickerView.dataSource = self


func updatePicker()
    self.pickerView.reloadAllComponents()


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


func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
    if serviceType.isFirstResponder
        return serviceArray.count
     else if brandsField.isFirstResponder
        return brandsArray.count
    
 //ERROR HERE

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? 
    if serviceType.isFirstResponder
        return serviceArray[row]
    else if brandsField.isFirstResponder
        return brandsArray[row]
    
  //ERROR HERE

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
    if serviceType.isFirstResponder
        let itemselected = serviceArray[row]
        serviceType.text = itemselected
    else if brandsField.isFirstResponder
        let itemselected = brandsArray[row]
        brandsField.text = itemselected
    

但它一直给我错误提示 "Missing return in a function expected to return String?" 和 "Missing return in a function expected to return int" 在我评论的地方。我能做什么？

【参考方案1】：

如果你想在pickerview中使用多个文本字段，你可以使用这个 UITextField 子类。

class PickerTextField: UITextField,UIPickerViewDelegate,UIPickerViewDataSource 

    let pickerView = UIPickerView()
    var itemList = [String]()

    override init(frame: CGRect) 
        super.init(frame: frame)
    
    required init?(coder aDecoder: NSCoder) 
        super.init(coder: aDecoder)
    
    @objc func textEdited(_ sender:PickerTextField)
    
        self.text = itemList[pickerView.selectedRow(inComponent: 0)]
    

    override func draw(_ rect: CGRect) 
        super.draw(rect)
        self.tintColor = UIColor.clear
        self.addTarget(self, action: #selector(textEdited(_:)), for: .editingChanged)
        pickerView.showsSelectionIndicator = true
        pickerView.delegate = self
        pickerView.dataSource = self
        self.inputView = pickerView

        let toolBar = UIToolbar()
        toolBar.barStyle = UIBarStyle.default
        toolBar.isTranslucent = true
        toolBar.tintColor = .black
        toolBar.sizeToFit()

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

        toolBar.items = [cancelButton, spaceButton, doneButton]
        self.inputAccessoryView = toolBar
    
    @objc func doneBtnAction(_ sender:UIBarButtonItem) 
        resignFirstResponder()
    
    func numberOfComponents(in pickerView: UIPickerView) -> Int 
        return 1
    
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
        return itemList.count
    
    func pickerView(_ pickerView: UIPickerView, attributedTitleForRow row: Int, forComponent component: Int) -> NSAttributedString? 
        let title = itemList[row]
        return NSAttributedString(string: title, attributes: [NSAttributedStringKey.foregroundColor:UIColor.black])
    
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
        self.text = itemList[row]
    

并在viewDidLoad中分配选项列表

class ViewController: UIViewController 

    @IBOutlet weak var serviceType: PickerTextField!
    @IBOutlet weak var brandsField: PickerTextField!

    override func viewDidLoad() 
        super.viewDidLoad()
        serviceType.itemList = ["Services", "others"]
        brandsField.itemList = ["Apple", "Samsung"]
    

将子类分配给文本字段。

结果

【讨论】：

伟大的编码，谢谢。

【参考方案2】：

您需要退回else 案例。

if serviceType.isFirstResponder
    return serviceArray.count
 else if brandsField.isFirstResponder
    return brandsArray.count    
 else 
  // insert your else case here
  return 0 // for example

【参考方案3】：

将这 3 个方法重构为 this ，因为如果所有 if 情况都没有命中，编译器将不知道返回什么，所以它给出了这个错误

func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int 
    if serviceType.isFirstResponder
        return serviceArray.count
     else 
        return brandsArray.count
    
 //ERROR HERE

func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? 
    if serviceType.isFirstResponder
        return serviceArray[row]
    else 
        return brandsArray[row]
    
  //ERROR HERE

func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) 
    if serviceType.isFirstResponder
        let itemselected = serviceArray[row]
        serviceType.text = itemselected
    else 
        let itemselected = brandsArray[row]
        brandsField.text = itemselected