Swift RealityKit–；异步模型加载不'；行不通

此代码适用于：

let entity = try! Entity.load(named: "toy_robot_vintage")
anchorEntity.addChild(entity)

但这并不是：

_ = Entity.loadAsync(named: "toy_robot_vintage")
        .sink(receiveCompletion: { loadCompletion in
            print("This is never executed")
        }, receiveValue: { entity in
            print("This is never executed")
            anchorEntity.addChild(entity)
        })

---

可能出现什么问题？

使用以下macOS代码版本了解如何异步加载模型：

import AppKit
import RealityKit
import Combine

class GameViewController: NSViewController {
    
    @IBOutlet var arView: ARView!
    var model: ModelEntity? = nil
    let anchor = AnchorEntity()
    var cancellable: AnyCancellable? = nil
    
    override func awakeFromNib() {
    
        arView.environment.background = .color(.systemTeal)
                
        cancellable = Entity.loadModelAsync(named: "Glasses.usdz")
            .sink(receiveCompletion: { completion in
                if case let .failure(error) = completion {
                    print("Unable to load a model due to error \(error)")
                }
                self.cancellable?.cancel()
                
            }, receiveValue: { [self] (model: Entity) in
                if let model = model as? ModelEntity {
                    self.model = model
                    cancellable?.cancel()
                    print("Congrats! Model is successfully loaded!")
                    anchor.addChild(model)
                    anchor.position = [0.4, 1.5, -1]
                    anchor.scale = [300, 300, 300]        // set appropriate scale
                    arView.scene.anchors.append(anchor)
                }
            })
    }
}

---

这很有效。非常感谢你。显然，有必要在loadModelAsync（）的闭包中取消从loadModelAsync（）返回的AnyCancelable。这不是取消AnyCancelable，而是保存对LoadRequest的引用，这样ARC就不会因为引用计数为零而将其从内存中踢出。我还建议将anycancelable设置为弱，以避免循环引用（GameViewController->closure->anycancelable）