带有 "external" DataSource 和 Swift 中的 Delegate 的 UIPickerView

Question

我的视图中有两个不同的 UIPickerView。当我将数据源和委托设置为它们通过故事板托管的视图时，它们工作得很好，但是当我尝试通过如下所述的代码执行此操作时，它不起作用。

两个选择器都应显示不同的数据（甚至可能代表不同的行为）。因此，我想以编程方式将它们连接到不同的数据源。

我试图创建自己的 class 实现 UIPickerViewDataSource 和 UIPickerViewDelegate 协议，并将 class 的对象连接到我的 PickerView，但它不起作用。运行时抛出异常 terminating with uncaught exception of type NSException 说明：

2015-01-09 17:50:05.333 Pet Stats[4953:244338] -[NSConcreteMapTable numberOfComponentsInPickerView:]: unrecognized selector sent to instance 0x7b4616d0
2015-01-09 17:50:05.338 Pet Stats[4953:244338] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSConcreteMapTable numberOfComponentsInPickerView:]: unrecognized selector sent to instance 0x7b4616d0'

我怎样才能让它工作？我错过了什么？这是我的代码：

WeightWheelController.swift

import UIKit

class WeightWheelController: NSObject, UIPickerViewDelegate, UIPickerViewDataSource {
    let ElementCount: Int!

    init(pickerInterval: Int) {
        ElementCount = pickerInterval
    }

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

    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return ElementCount
    }

    func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
        return String(row + 1)
    }

    func pickerView(pickerView: UIPickerView!, didSelectRow row: Int, inComponent component: Int)
    {
        println("External Controller:" + String(row + 1))
    }
}

WeightWheelInputViewController.swift

import UIKit

class WeightWheelInputViewController: UIViewController {
    @IBOutlet weak var picker1: UIPickerView!        
    @IBOutlet weak var picker2: UIPickerView!

    override func viewDidLoad() {
        super.viewDidLoad()

        //picker attached to c1 should show number from 1 to 150
        let c1 = WeightWheelController(pickerInterval: 150)

        //picker attached to c1 should show number from 1 to 10
        let c2 = WeightWheelController(pickerInterval: 10)

        picker1.dataSource = c1
        picker1.delegate = c1

        picker2.dataSource = c2
        picker2.delegate = c2
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

简要更新：

在这个问题中，我发现您可以为不同的选择器视图使用不同的标签。那将是一种选择；然而，我不喜欢它。我宁愿遵循 MVC'ish 方法并将不同的控制器连接到每个选择器。这不可能吗？

Answer 1

delegate 和 datasource 都是无主引用。这意味着 c1 和 c2 将在您超出范围后立即释放。尝试将 c1 和 c2 声明为 class.

的属性

Unowned 引用不会对被引用对象创建强保留（a.k.a。它们不会增加保留计数以防止 ARC 释放被引用对象）。

还要确保从界面构建器中删除了 pickerviews 的委托和数据源属性。

class WeightWheelInputViewController: UIViewController {
    @IBOutlet weak var picker1: UIPickerView!        
    @IBOutlet weak var picker2: UIPickerView!

    var c1 : WeightWheelController!
    var c2 : WeightWheelController!

    override func viewDidLoad() {
        super.viewDidLoad()

        c1 = WeightWheelController(pickerInterval: 150)

        c2 = WeightWheelController(pickerInterval: 10)

        picker1.dataSource = c1
        picker1.delegate = c1

        picker2.dataSource = c2
        picker2.delegate = c2
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

带有 "external" DataSource 和 Swift 中的 Delegate 的 UIPickerView

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