当我提供init（）函数时，为什么会调用init（coder :)

Question

我正在使用SpriteKit，并且我正在加载一个SceneKit文件，该文件包含一些使用自定义类的sprites。场景从未实际加载，因为它到达第一个自定义类并从required init?(coder:)初始值设定项引发fatalerror。虽然自定义类实现了一个初始化器，但我无法确定为什么它会选择我提供的初始化器。

自定义类：

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() {} 
} 

这里是试图通过孩子来加载场景，然后循环并进行初始化代码：

遭遇经理：

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 
    } 
    } 
} 

我注意到使用断点虽然它永远不会过去加载场景。它在行if let encounterScene = SKScene(fileNamed: encounterFileName)上失败，错误是来自Bat类的初始化程序中的致命错误。

任何帮助理解为什么它会选择一个初始化器将不胜感激！

Answer 1

你正在做的：

if let encounterScene = SKScene(fileNamed: encounterFileName) 

其中要求SKScene的init(fileNamed:)它加载一个文件，并SKScene的编码器初始化解码。该init会加载该文件并使用节点的编码器init对其中的每个元素进行解码。

如果你想从一个文件加载，你需要实现编码器初始化。