无法将“NSMutableArray”类型的值转换为预期的参数类型“[SKTexture]”

Question

我收到以下代码错误：

func prepareAnimationForDictionary(settings: NSDictionary,repeated: Bool) -> SKAction {
        let atlas: SKTextureAtlas = 
          SKTextureAtlas(named: settings["AtlasFileName"] as! String)
        let textureNames:NSArray = settings["Frames"] as! NSArray
        let texturePack: NSMutableArray = []

        for texPath in textureNames {
            texturePack.addObject(atlas.textureNamed(texPath as! String))
        }

        let timePerFrame: NSTimeInterval = Double(1.0/(settings["FPS"] 
         as! Float))

        let anim:SKAction = SKAction.animateWithTextures(texturePack, 
          timePerFrame: timePerFrame) // the error I get is here
        if repeated {
        return SKAction.repeatActionForever(anim)
        }else{
        return anim
        }

Answer 1

只需使用预期的 (Swift) 类型

...
let textureNames = settings["Frames"] as! [String]
var texturePack =  [SKTexture]()

for texPath in textureNames {
    texturePack.append(atlas.textureNamed(texPath))
}
...

从 Swift 的角度来看，可变 Foundation 集合类型 NSMutableArray 和 NSMutableDictionary 是未指定类型的，与 Swift 本机对应物无关。

Answer 2

更改timePerFrame 给(timePerFrame as [AnyObject]) as! [SKTexture]

Answer 3

好的，考虑一下。你有一个变量texturePack。您没有显示声明，但根据错误消息，我将假设它的类型为 NSMutableArray。有问题的调用需要一个 SKTexture 对象数组。

因此，请将您的 texturePack 转换为所需的类型：

let anim:SKAction = SKAction.animateWithTextures(texturePack as! [SKTexture], 
  timePerFrame: timePerFrame) //error i get is here

请注意，如果 texturePack 不是 SKTexture 对象的数组，您最好使用 if let 或 guard 来检查转换是否成功：

guard 
  let anim:SKAction = SKAction.animateWithTextures(texturePack as! [SKTexture], 
    timePerFrame: timePerFrame) //error i get is here
else
{
  return nil;
}

或者，正如其他人所建议的，将 texturePack 数组的声明更改为 [SKTexture] 类型