类型'x'不符合协议'UIPickerViewDataSource'

Question

    import UIKit

class FourthViewController: UIViewController,UIPickerViewDelegate,UIPickerViewDataSource {


    @IBOutlet weak var picker: UIPickerView!

      var pickerData: [String] = [String]()


    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.

        self.picker.delegate = self
        self.picker.dataSource = self

        pickerData = ["Item 1", "Item 2", "Item 3", "Item 4", "Item 5", "Item 6"]    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    //MARK: - Delegates and data sources
    //MARK: Data Sources
    func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
        return 1
    }
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return pickerData.count
    }

    //MARK: Delegates
    func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
        return pickerData[row]
    }
    /*
    // MARK: - Navigation

    // In a storyboard-based application, you will often want to do a little preparation before navigation
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        // Get the new view controller using segue.destinationViewController.
        // Pass the selected object to the new view controller.
    }
    */

}

错误：类型'FourthViewController'不符合协议'UIPickerViewDataSource'

只是为了测试一些功能，但我没有得到问题

Answer 1

如您numberOfComponents(in:) ，您需要实现numberOfComponents(in:) 。

你的numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int ，需要改为：

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

你还需要修改你的pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? ：

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

在Swift 3中，许多方法都被重命名。 检查最新的参考 ，并注意这一点 。 你最好在你的问题中评论Xcode版本。

Answer 2

您必须符合数据源协议：

public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int

试试这段代码：

//MARK: - Delegates and data sources
        //MARK: Data Sources
        public func numberOfComponents(in pickerView: UIPickerView) -> Int {
            return 1
        }

        public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
            return pickerData.count
        }

        //MARK: Delegate
        func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
            return pickerData[row]
        }

Answer 3

如果在swift确认该协议，则必须实现UIPickerViewDataSource和UIPickerViewDelegate所需的所有方法。 否则它会在编译时给出错误。

Answer 4

由于委托方法，我收到错误

func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int 
    {
    if pickerView == stylePickerView {
        return 1        }
    else if pickerView == fontPickerView {
        return 1        }
    return 0
    }

试过这个并且工作了

@available(iOS 2.0, *)
public func numberOfComponents(in pickerView: UIPickerView) -> Int {
    if pickerView == stylePickerView {
        return 1        }
    else if pickerView == fontPickerView {
        return 1        }
    return 0 
}

Answer 5

您在委托中遗漏了这个：

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