ios - 我收到诸如 "braced block of statements is an unused closure"和预期表达式之类的错误

Question

这是我第一次在 swift 中做一个简单的项目，这些错误困扰了我几个小时。我在下面有这段代码，即使我在 if/else 中有花括号和语句，我仍然会遇到这些错误。任何帮助将不胜感激。

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var `switch`: UISwitch!
    @IBOutlet var Answer: UILabel!
    @IBOutlet var tempInput: UITextField!


    //aqnswer value

    @IBAction func switchPressed(sender: AnyObject)
    {
        if switch.on {

            self.Answer.text = "cel to fah"
        }
        else {

            self.Answer.text = "fah to cel"
        }

    }
        //textfield value



    @IBAction func calculate(sender: AnyObject)
            {
                //get user input 
                // value = celcius

                 var Value:Int = tempInput.text.toInt()!

                var toFah :Int = ( 32 + Value * 9 ) / 5

                //to celcius

                var toCel: Int = (Value-32) * 5 / 9

                if switch.on {



                    self.Answer.text = toFah.description
                }

                else {
                self.Answer.text = toCel.description
                }






               // println(fah)

               // Answer.text = fah.description


                }



    override func viewDidLoad() {

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

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


}

Answer 1

Swift 语言指南说:

If you need to give a constant or variable the same name as a reserved Swift keyword, surround the keyword with back ticks (`) when using it as a name. However, avoid using keywords as names unless you have absolutely no choice.

在你的例子中你确实有一个选择......

但是如果你真的真的真的想使用 switch 作为变量名，你必须将 所有 出现的 switch 包含在反引号中。