UIPickerView在Swift中使用"外部"DataSource和Delegate

Question

我的视图中有两个不同的UIPickerView.当我将dataSource和委托设置为通过故事板托管的View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.

两个选择器都应该有不同的数据来显示(甚至可能是委托的不同行为).因此,我想以编程方式将它们连接到不同的数据源.

我试图创建我自己的类,实现UIPickerViewDataSource-和UIPickerViewDelegate-Protocols,并将该类的对象连接到我的PickerViews,但它不起作用.在运行时抛出异常,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'

我怎样才能让它发挥作用？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.这将是一种选择; 但是,我不喜欢它.我想宁愿遵循MVC'的方法,并将不同的控制器连接到每个选择器.这有可能吗？

Answer 1

这两个delegate和datasource是无主引用.这意味着,c1和c2将得到只要你走出去的范围释放.尝试声明c1和c2作为类的属性.

无主引用不会对引用对象产生强烈保持(也就是说它们不会增加保留计数以防止ARC释放引用对象).

还要确保从界面构建器中删除选取器视图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()
    }
}