为什么在我提供 init() 函数时调用 init(coder:)

Question

我正在使用 SpriteKit，我正在加载一个 SceneKit 文件，其中包含许多具有自定义 classes 的精灵。场景实际上从未加载过，因为它到达第一个自定义 class 并从 required init?(coder:) 初始化程序中抛出 fatalerror。尽管自定义 class 实现了一个初始化程序，但我无法确定为什么它选择该初始化程序而不是我提供的初始化程序。

自定义 Class:

class Bat: SKSpriteNode, GameSprite {
  var initialSize: CGSize = CGSize(width: 44, height: 24)
  var textureAtlas: SKTextureAtlas = SKTextureAtlas(named: "Enemies")
  var flyAnimation = SKAction()

  init() {
    super.init(texture: nil, color: .clear, size: initialSize)

    self.physicsBody = SKPhysicsBody(circleOfRadius: size.width / 2)
    self.physicsBody?.affectedByGravity = false

    createAnimations()
    self.run(flyAnimation)
  }

  required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") }

  func createAnimations() {
    let flyFrames: [SKTexture] = [textureAtlas.textureNamed("bat"),
                                  textureAtlas.textureNamed("bat-fly")]

    let flyAction = SKAction.animate(with: flyFrames, timePerFrame: 0.12)
    flyAnimation = SKAction.repeatForever(flyAction)
  }

  func onTap() {}
}

下面是尝试加载场景然后遍历子项并初始化它们的代码：

遇到经理：

class EncounterManager {
  // Store encounter file names
  let encounterNames: [String] = [
    "EncounterA"
  ]

  // Each encounter is a node, store an array
  var encounters: [SKNode] = []

  init() {
    // Loop through each encounter scene and create a node for the encounter
    for encounterFileName in encounterNames {
      let encounterNode = SKNode()

      // Load the scene file into a SKScene instance and loop through the children
      if let encounterScene = SKScene(fileNamed: encounterFileName) {
        for child in encounterScene.children {

          // Create a copy of the scene's child node to add to our encounter node
          // Copy the position, name, and then add to the encounter
          let copyOfNode = type(of: child).init()
          copyOfNode.position = child.position
          copyOfNode.name = child.name
          encounterNode.addChild(copyOfNode)
        }
      }

      // Add the populated encounter node to the array
      encounters.append(encounterNode)
    }
  }

  // This function will be called from the GameScene to add all the encounter nodes to the world node
  func addEncountersToScene(gameScene: SKNode) {
    var encounterPosY = 1000

    for encounterNode in encounters {
      // Spawn the encounters behind the action, with increasing height so they do not collide
      encounterNode.position = CGPoint(x: -2000, y: encounterPosY)
      gameScene.addChild(encounterNode)

      // Double Y pos for next encounter
      encounterPosY *= 2
    }
  }
}

我注意到使用断点时它永远不会超过加载场景。它在 if let encounterScene = SKScene(fileNamed: encounterFileName) 行失败，错误是 Bat class.

初始化程序中的致命错误

如果能帮助理解为什么选择一个初始化器而不是另一个初始化器，我们将不胜感激！

Answer 1

你正在做：

 if let encounterScene = SKScene(fileNamed: encounterFileName)

调用 SKScene 的 init(fileNamed:) 加载文件并使用 SKScene 的编码器初始化对其进行解码。该 init 加载文件并使用节点的编码器 init 解码其中的每个元素。

如果要从文件加载，需要实现编码器初始化。

为什么在我提供 init() 函数时调用 init(coder:)

Why is init(coder:) being called when I provide an init() function

sprite-kit

skspritenode

swift

swift3