UserDefaults 的 Switch 语句 (Swift-Xcode)答案

【问题标题】：Switch statement for UserDefaults (Swift-Xcode)UserDefaults 的 Switch 语句 (Swift-Xcode)
【发布时间】：2018-01-22 04:14:41
【问题描述】：

我想知道如何为用户默认值做一个 switch-case/任何好的语句，而不是使用 if-else，因为从我的代码中可以看出，我使用了 3 个 if 语句，这有点多余并且丑陋。此视图控制器的目的是用于“选卡”游戏，用户每次可以选择 3 张卡，如果他/她选择了一张卡，他们将无法再次选择该特定卡。

import UIKit

class ViewController: UIViewController {
    @IBOutlet var buttona: UIButton!
    @IBOutlet var buttonb: UIButton!
    @IBOutlet var buttonc: UIButton!

    override func viewDidLoad() {
       super.viewDidLoad()
       if (UserDefaults.standard.integer(forKey: "dissapear") == 1)
       {
           buttona.setImage(UIImage(named: "wildcardbackingblack.png"), for: .normal)
           buttona.isEnabled = false
       }

       if (UserDefaults.standard.integer(forKey: "dissapear2") == 1)
       {
           buttonb.setImage(UIImage(named: "wildcardbackingblack.png"), for: .normal)
           buttonb.isEnabled = false
       }

       if (UserDefaults.standard.integer(forKey: "dissapear3") == 1)
       {
           buttonc.setImage(UIImage(named: "wildcardbackingblack.png"), for: .normal)
           buttonc.isEnabled = false
       }
   }

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

   @IBAction func Button1(_ sender: Any) {
      UserDefaults.standard.set(1, forKey:"dissapear")
      self.performSegue(withIdentifier: "show", sender: nil)         
   }

   @IBAction func Button2(_ sender: Any) {
      UserDefaults.standard.set(1, forKey:"dissapear2")
      self.performSegue(withIdentifier: "show", sender: nil)
   }

   @IBAction func Button3(_ sender: Any) {
      UserDefaults.standard.set(1, forKey:"dissapear3")
      self.performSegue(withIdentifier: "show", sender: nil)
    }
 }

【问题讨论】：

你重复自己太多了。将常用代码提取到函数中，循环遍历[(buttona, "dissapear"), (buttonb, "dissapear2"), (buttonc, "dissapear3")]，并调用它
@Alexander 你是怎么做到的？我对迅速道歉还是很陌生

标签： ios swift xcode switch-statement

【解决方案1】：

    func updateCard(button: UIButton, image: String, isEnabled: Bool) {
        DispatchQueue.main.asyc {
            button.setImage(UIImage(named:image), for: .normal)
            button.isEnabled = isEnabled
        }
    }

    .
    .
    .

    let option : Int = UserDefaults.standard.integer(forKey: "dissapear")
    switch (option) {
        case 1:
            self.updateCard(button: ..., image:"wildcardbackingblack.png", isEnabled: false)
        case 2:                       
            self.updateCard(button: ..., image:"wildcardbackingblack.png", isEnabled: false)
        case 3:
            self.updateCard(button: ..., image:"wildcardbackingblack.png", isEnabled: false)
        default:
            self.updateCard(button: ..., image:"default.png", isEnabled: false)
    } 
//Save the different integer value in same key user defaults.

 @IBAction func Button1(_ sender: Any) {
      UserDefaults.standard.set(1, forKey:"dissapear")
      self.performSegue(withIdentifier: "show", sender: nil)         
   }

   @IBAction func Button2(_ sender: Any) {
      UserDefaults.standard.set(2, forKey:"dissapear")
      self.performSegue(withIdentifier: "show", sender: nil)
   }

   @IBAction func Button3(_ sender: Any) {
      UserDefaults.standard.set(3, forKey:"dissapear")
      self.performSegue(withIdentifier: "show", sender: nil)
    }

【讨论】：

您的回答可能会有所帮助，但仅发布代码并不是最佳答案。如果您添加一些解释，那么它将有助于其他面临同样问题的人。所以添加一些与答案相关的信息是一个好习惯:)
OP 应该将 1/2/3 替换为更有意义的值（卡片名称？）

【解决方案2】：

如果我坚持使用相同的 UserDefaults 存储，这就是我将如何编写此代码的方法。注意：您需要将cardPressed(_:) 重新连接到每个按钮/卡片

import UIKit

class ViewController: UIViewController {
    @IBOutlet var buttonA: UIButton!
    @IBOutlet var buttonB: UIButton!
    @IBOutlet var buttonC: UIButton!

    let buttonKeyPairs: [(button: UIButton, key: String)] = [
        (buttonA, "dissapear"),
        (buttonB, "dissapear2"),
        (buttonC, "dissapear3"),
    ]

    override func viewDidLoad() {
        super.viewDidLoad()

        for (button, key) in buttonKeyPairs
            where UserDefaults.standard.integer(forKey: key) == 1 {

            button.setImage(UIImage(named: "wildcardbackingblack.png"), for: .normal)
            button.isEnabled = false
        }
    }

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

    @IBAction func buttonPressed(_ sender: UIButton) {
        let key: String
        switch UIButton {
            case buttonA: key = "dissapear"
            case buttonB: key = "dissapear2"
            case buttonC: key = "dissapear3"
        }
        UserDefaults.standard.set(1, forKey: key)
        self.performSegue(withIdentifier: "show", sender: self)         
    }
}

【讨论】：