ios - 类型 'x' 不符合协议(protocol) '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.
    }
    */

}

Error:Type 'FourthViewController' does not conform to protocol 'UIPickerViewDataSource'

只是为了测试一些功能，但我没有得到问题

Answer 1

如您所见，您需要实现 numberOfComponents(in:)。

您的 numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int，需要更改为:

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了。检查the latest reference , 注意 this .你最好在问题中注明 Xcode 版本。