ios - 'CountableClosedRange' 类型的表达式模式无法匹配 'Int' 类型的值？

Question

在 Swift 3 之前，这段代码可以正常工作，没有任何编译错误，但是在转换为 Swift 3 之后，这段代码无法编译，我不完全理解值类型有何不同。

给出的错误是expression pattern of type 'CountableClosedRange<Int>' cannot match values of type 'Int'对于我尝试在 switch 语句中使用不同范围的值的 switch 情况:

switch hour {
        case 0 ... 11:
            greetingStatement.text = "Good Morning"
        case 12 ... 24:
            greetingStatement.text = "Good Evening"
        default:
            greetingStatement.text = "Hello"
        }

完整代码如下:

import UIKit

class ViewController: UIViewController {


    @IBOutlet weak var userInput: UITextField!
    @IBOutlet weak var usertOutput: UILabel!

    @IBOutlet weak var tapMeAfterEnteringYourName: UIButton!

    @IBOutlet weak var greetingStatement: UILabel!
    @IBOutlet weak var letsGetStartedLabel: UILabel!

    @IBOutlet weak var ballonsImageView: UIImageView!
    @IBOutlet weak var teacherPointingToBoardImage: UIImageView!
    @IBAction func setOutput(_ sender: AnyObject){
        greetingStatement.isHidden = false
        usertOutput.text=userInput.text
        tapMeAfterEnteringYourName.isHidden = true
        userInput.isHidden = true
        letsGetStartedLabel.isHidden = false
        ballonsImageView.isHidden = false

        let date = Date()
        let calendar = Calendar.current
        let components = (calendar as NSCalendar).components([.hour], from: date)
        let hour = components.hour
        switch hour {
        case 0 ... 11:
            greetingStatement.text = "Good Morning"
        case 12 ... 24:
            greetingStatement.text = "Good Evening"
        default:
            greetingStatement.text = "Hello"
        }
        view.backgroundColor = UIColor.magenta
        teacherPointingToBoardImage.isHidden=true

        var timer = Timer.scheduledTimer(timeInterval: 1.4, target: self, selector: #selector(ViewController.updateViewController), userInfo: nil, repeats: false)


        let hover = CABasicAnimation(keyPath: "position")
        hover.isAdditive = true
        hover.fromValue = NSValue(cgPoint: CGPoint.zero)
        hover.toValue = NSValue(cgPoint: CGPoint(x: 0.0, y: -100.0))
        hover.autoreverses = true
        hover.duration = 5
        hover.repeatCount = Float.infinity
        ballonsImageView.layer.add(hover, forKey: "myHoverAnimation")



    }

    func updateViewController() {

        print("Timer just fired")
        let storyBoard : UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
        let resultViewController = storyBoard.instantiateViewController(withIdentifier: "MadLibOneViewController") as! MadLibOneViewController
        self.present(resultViewController, animated:true, completion:nil)

    }

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor=UIColor.purple
        usertOutput.textColor=UIColor.white
        userInput.textColor = UIColor.purple
        greetingStatement.isHidden = true
        letsGetStartedLabel.isHidden = true
        ballonsImageView.isHidden = true







    }

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


}

有人可以澄清这只是一个泛型，其中允许或期望任何类型的 Int 吗？

Answer 1

该错误具有误导性。问题是 hour 是一个可选的 Int。

我会将代码更改为:

if let hour = components.hour {
    switch hour {
    case 0 ... 11:
        greetingStatement.text = "Good Morning"
    case 12 ... 24:
        greetingStatement.text = "Good Evening"
    default:
        greetingStatement.text = "Hello"
    }
}