如何从另一个视图控制器中调用Uipickerview子类中的方法

Question

我有一个我的 UIPickerView，我正在划分，效果很好。但是，我有一种需要调用的方法来"重置"它正在查看的UiviewController。但是，它永远不会开火。如何从另一个视图控制器调用func resetPicker()？

import Foundation
import UIKit
class ScoreClockPicker: UIPickerView {
    //PickerView
    let timerMinutesArray = Array(00...20)
    let timerSecondsArray = Array(00...59)
    let periodArray = ["1st", "2nd", "3rd", "OT", "SO"]
    //Picker return values
    var numberOfRowsInComponentReturnValue = 0
    var titleForRowReturnValue             = ""
    var widthForComponentReturnValue       = ""

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.delegate   = self
        self.dataSource = self
    }
    func resetPicker() {
        print("resetPicker")
        self.selectRow(0, inComponent: 0, animated: true)
        self.selectRow(0, inComponent: 1, animated: true)
        self.selectRow(0, inComponent: 3, animated: true)
    }
}
extension ScoreClockPicker: UIPickerViewDataSource {
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        if component == 0 {
            numberOfRowsInComponentReturnValue =  periodArray.count
        } else if component == 1 {
            numberOfRowsInComponentReturnValue = timerMinutesArray.count
        } else if component == 2 {
            numberOfRowsInComponentReturnValue = 1
        } else if component == 3 {
            numberOfRowsInComponentReturnValue = timerSecondsArray.count
        }
        return numberOfRowsInComponentReturnValue
    }
    func numberOfComponents(in pickerView: UIPickerView) -> Int {
        return 4
    }
    func pickerView(_ pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
        var componentWidth = 0
        if component == 0 {
            componentWidth = 140
        } else if component == 1 {
            componentWidth = 40
        } else if component == 2 {
            componentWidth = 30
        } else if component == 3 {
            componentWidth = 40
        }
        return CGFloat(componentWidth)
    }

}
extension ScoreClockPicker: UIPickerViewDelegate {
    func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        print("didSelectRow")
    }
    func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        if component == 0 {
            titleForRowReturnValue =  periodArray[row]
        } else if component == 1 {
            titleForRowReturnValue =  String(describing: timerMinutesArray[row])
        } else if component == 2 {
            titleForRowReturnValue =  ":"
        } else if component == 3 {
            titleForRowReturnValue =  String(format: "%02d",timerSecondsArray[row])
        }
        return titleForRowReturnValue
    }
}

编辑：

以下内容无法从访问ScoreClockPicker的ViewController起作用：

import UIKit
class ScoreClockViewController: UIViewController {
    @IBOutlet weak var resetButton: UIButton!
    @IBOutlet weak var okButton: UIButton!
   var picker: ScoreClockPicker?
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        //Hide the Navigation Bar
        self.navigationController?.setNavigationBarHidden(false, animated: true)
    }
    //@IBOutlet
    @IBAction func reset(_ sender: Any) {
        print("reset")
        picker?.resetPicker() //Call the ScoreClockPicker
//        picker?.selectRow(0, inComponent: 0, animated: true)
//        picker?.selectRow(0, inComponent: 1, animated: true)
//        picker?.selectRow(0, inComponent: 3, animated: true)
    }
    @IBAction func ok(_ sender: Any) {
    }

}

Answer 1

从您的代码中，您尚未初始化要在按钮操作中使用的picker对象。因此，在使用之前只需初始化picker。

如果您要制作ScoreClockPicker的出口，则

@IBOutlet var picker: ScoreClockPicker!

或您可以在viewDidLoad中初始化picker

self.picker = ScoreClockPicker()