PickerView:类型'ViewController‘不符合协议'UIPickerViewDataSource’

Question

我正在使用示例项目中的代码。它确实在示例项目中工作，但在我的项目中不起作用。

SettingsViewController.swift:

import UIKit

class ViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {
    let days:[String] = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

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

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

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

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


}

我正在使用Xcode 8.2.1，Swift 2.3

Answer 1

numberOfComponents(in:)的方法签名从iOS 9.3更改为iOS 10。由于您的目标是Swift的旧版本，所以用下面的适当版本替换当前的numberOfComponents(in:)实现。

Swift 2.3

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

Swift 3

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

API的变化可以在这里看到：https://developer.apple.com/library/content/releasenotes/General/iOS10APIDiffs/Swift/UIKit.html

改性UIPickerViewDataSource

声明

从…

protocol UIPickerViewDataSource : NSObjectProtocol {
    func numberOfComponentsInPickerView(_ pickerView: UIPickerView) -> Int
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
}

至

protocol UIPickerViewDataSource : NSObjectProtocol {
    func numberOfComponents(in pickerView: UIPickerView) -> Int
    func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int
}