傳遞數據從彈出的ViewController回用斯威夫特

Question

我想知道我們如何通過數據回從彈出的ViewController

FirstViewController -----push----> SecondViewController 

SecondViewController -----popped(Pass Value?) ----> FirstViewController 

我尋覓了一圈，發現許多解決方案要求使用委託，但那些在我不熟悉的Objective C中。

我們如何在Swift中做到這一點？

謝謝

Answer 1

其實代表們不只是在客觀C.代表團提供可在斯威夫特（任何不涉及的Objective-C的動態特性能夠在斯威夫特）和授權是一種設計模式（ delegation as a design pattern），而不是語言實現。您可以使用兩種方法之一，塊/閉包或委派。在迅速代表團的一個例子蘋果的文檔中找到如下參考：

Apple documentation on delegation

您還可以看到在關閉了蘋果的文檔參考這裏： Apple documentation on closures

可以證明代表團的一個例子下面：

注意，委託通過下面的協議宣稱：

protocol DiceGame { 
    var dice: Dice { get } 
    func play() 
} 
protocol DiceGameDelegate { 
    func gameDidStart(game: DiceGame) 
    func game(game: DiceGame, didStartNewTurnWithDiceRoll diceRoll: Int) 
    func gameDidEnd(game: DiceGame) 
} 

個

類檢查其是否具有一個委託，如果是這樣，它調用的類必須由符合上述

class SnakesAndLadders: DiceGame { 
     let finalSquare = 25 
     let dice = Dice(sides: 6, generator: LinearCongruentialGenerator()) 
     var square = 0 
     var board: [Int] 
     init() { 
      board = [Int](count: finalSquare + 1, repeatedValue: 0) 
      board[03] = +08; board[06] = +11; board[09] = +09; board[10] = +02 
      board[14] = -10; board[19] = -11; board[22] = -02; board[24] = -08 
     } 
     var delegate: DiceGameDelegate? 
     func play() { 
      square = 0 
      delegate?.gameDidStart(self)//Calls the method gameDidEnd on the delegate passing self as a parameter 
      gameLoop: while square != finalSquare { 
       let diceRoll = dice.roll() 
       delegate?.game(self, didStartNewTurnWithDiceRoll: diceRoll) 
       switch square + diceRoll { 
       case finalSquare: 
        break gameLoop 
       case let newSquare where newSquare > finalSquare: 
        continue gameLoop 
       default: 
        square += diceRoll 
        square += board[square] 
       } 
      } 
      delegate?.gameDidEnd(self)//Calls the method gameDidEnd on the delegate passing self as a parameter 
     } 
    }