swift – 克隆节点时SceneKit泄漏

class AssetLoader {
    fileprivate var rootNodes = Dictionary<String,SCNNode>()

    static let sharedInstance = AssetLoader()

    fileprivate init() {
    }

    func rootNode(_ named: String) -> SCNNode {
        if self.rootNodes[named] != nil {
            return self.rootNodes[named]!.clone()
        } else {
            let scene = SCNScene(named: "art.scnassets/(named).scn")
            self.rootNodes[named] = scene!.rootNode
            return self.rootNodes[named]!.clone()
        }
    }
}

我用它来让我的场景建设更快.我正在从扩展创建资产：

extension CAAnimation {
    class func animationWithScene(named: String) -> CAAnimation? {
        unowned let rootNode = AssetLoader.sharedInstance.rootNode(named)
        var animation: CAAnimation?

        rootNode.enumerateChildNodes({ (child,stop) in
            if child.animationKeys.count > 0 {
                animation = child.animation(forKey: child.animationKeys.first!)
                stop.initialize(to: true)
            }
        })
        return animation
    }
}

extension SCNNode {
    class func nodeWithScene(named: String) -> SCNNode? {
        unowned let rootNode = AssetLoader.sharedInstance.rootNode(named)
        let node = SCNNode()

        for child in rootNode.childNodes {
            node.addChildNode(child)
        }

        node.eulerAngles = SCNVector3(x: Float(-M_PI_2),y: 0,z: 0)
        node.scale = SCNVector3Make(kMeshScale,kMeshScale,kMeshScale)

        return node
    }
}

乐器说我在每次调用clone()时都会疯狂地泄漏内存.我试图在没有造成崩溃的情况下尽可能使用弱而无主,并且它不会改变任何东西.有人有线索吗？这是SceneKit中的错误吗？

谢谢