快速从 UIPickerView 的选定行设置 UIButton 的标题

Question

我正在尝试从 uipickerview 的选定行中设置我的按钮标题。但是，我似乎找不到有效的解决方案。

我已将变量设置为全局变量，因此我可以访问选定变量。但是，我似乎无法准确指出用户何时单击退出按钮并能够更新我的按钮标题。

我尝试过的事情：

• 全局函数（无法工作，因为您无法指定要更改名称的按钮）
• Dispatchqueue.main.async - 没有更新我的标题。这里的想法是让它不断检查字符串的变化。

我在这里找到的解决方案是在 Obj-C 中。我尝试将其转换为 swift https://objectivec2swift.com/#/converter/code/，但没有成功。 Set Title of UIButton from Selected Row of UIPickerView

@IBAction func CountryPickButton(_ sender: UIButton) {

        Global.setPickerDataSource(data:["Test","test2","test3"])
        Global.setPickerCompletionHandler(int:0)
        let popOverVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "PickerViewPopUpId") as! PickerViewController
        //CountryPickButtonDetector = sender as? UIButton
        self.addChild(popOverVC)
        popOverVC.view.frame = self.view.frame
        self.view.addSubview(popOverVC.view)
        popOverVC.didMove(toParent: self)
        popOverVC.callback { value in
        //CountryPickButton.title.text = value
        sender.setTitle(value, for: UIControl.State)
    }
    }

---

import UIKit
var test = ""

class PickerViewController: UIViewController {
    @IBOutlet weak var PickerView: UIPickerView!
    var callback : ((String) -> Void)?
    override func viewDidLoad() {
        super.viewDidLoad()
        //self.view.backgroundColor = UIColor.black.withAlphaComponent(0.8)
        PickerView.dataSource = self
        PickerView.delegate = self
        // Do any additional setup after loading the view.
    }
    @IBAction func ExitButton(_ sender: Any) {
        switch Global.pickerCompletionHandler {

        case 0:
            callback?(Global.pickerResult ?? "")
            Global.setProfileCountry(string:
                Global.pickerResult ?? "")
        default:
            print("nothing")

        }
        self.view.removeFromSuperview()
    }

}

extension PickerViewController: UIPickerViewDelegate, UIPickerViewDataSource {
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 1 // can be more than 1 component like time/date/year
    }

    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return Global.pickerDataSource?.count ?? 1
    }

    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        //Global.pickerResult = Global.pickerDataSource?[row]
        Global.setPickerResult(result: Global.pickerDataSource?[row] ?? "Test" )
    }

    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return Global.pickerDataSource?[row]
    }


}

---

全局

import Foundation

struct Global {
    static var pickerDataSource:[String]? = nil
    static var pickerResult:String? = nil
    static var pickerCompletionHandler:Int? = 0
    static var profileCountry:String? = nil

    static func setPickerDataSource(data:[String]) {
        Global.pickerDataSource = data
    }
    static func setPickerResult(result:String) {
        Global.pickerResult = result
    }
    static func setPickerCompletionHandler(int: Int) {
        Global.pickerCompletionHandler = int
    }
    static func setProfileCountry(string: String)
    {
        Global.profileCountry = string
    }
}

Answer 1

我不知道Global 的全部内容是什么，最简单的解决方案可能是扩展pickerCompletionHandler，但这是另一个（简单）的解决方案：

• 在PickerViewController 中添加一个回调，传递一个String 值并且没有返回值

  var callback : ((String) -> Void)?
  

  并在exitButton 中调用它（请变量名和函数名应该以小写字母开头）

  @IBAction func exitButton(_ sender: Any) {
      switch Global.pickerCompletionHandler {
  
      case 0:
          callback?(Global.pickerResult ?? "")
          Global.setProfileCountry(string:
              Global.pickerResult ?? "")
      default:
          print("nothing")
  
      }
      self.view.removeFromSuperview()
  }
  

• 在countryPickButton（同样：小写字母）中设置回调并将sender设置为真实类型。回调设置标题

  @IBAction func countryPickButton(_ sender: UIButton) {
  
      Global.setPickerDataSource(data:["Test","test2","test3"])
      Global.setPickerCompletionHandler(int:0)
      let popOverVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "PickerViewPopUpId") as! PickerViewController
      popOverVC.callback = { value in 
          sender.setTitle(value, for: .normal)
      }
  ...