实例成员“addChild”不能用于“AnchorEntity”类型答案

【问题标题】：Instance member 'addChild' cannot be used on type 'AnchorEntity'实例成员“addChild”不能用于“AnchorEntity”类型
【发布时间】：2020-10-05 02:26:08
【问题描述】：

我一直在学习 Swift 和 ARKit，所以请原谅我草率的编码。我使用下面的两个教程来创建我现有的代码。我从第一个开始，然后在第二个视频的最后出现错误。 youtuber没有发生这种情况，所以我不确定我哪里出错了。完整的错误显示“实例成员 'addChild' 不能用于类型 'AnchorEntity'；您的意思是改用这种类型的值吗？”

任何帮助都是极大的感激不尽！

import UIKit

import RealityKit

import ARKit

class ViewController: UIViewController {

 @IBOutlet var arView: ARView!

 override func viewDidLoad() {
    super.viewDidLoad()
 
    arView.session.delegate = self
    
    showModel()
    overlayCoachingView()
    setupARView()
    
    arView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: 
#selector(handleTap(recognizer:))))
    
}

func showModel(){
    
    let anchorEntity = AnchorEntity(plane: .horizontal, minimumBounds:[0.2, 0.2])
    
    let entity = try! Entity.loadModel(named: "fender_stratocaster")
    entity.setParent(anchorEntity)
    
    arView.scene.addAnchor(anchorEntity)
    
}
func overlayCoachingView () {
    
    let coachingView = ARCoachingOverlayView(frame: CGRect(x: 0, y: 0, width: 
 arView.frame.width, height: arView.frame.height))
    
    coachingView.session = arView.session
    coachingView.activatesAutomatically = true
    coachingView.goal = .horizontalPlane
    
    view.addSubview(coachingView)
    
 }
    
    // Load the "Box" scene from the "Experience" Reality File
   // let boxAnchor = try! Experience.loadBox()
    
    // Add the box anchor to the scene
    //arView.scene.anchors.append(boxAnchor)

 func setupARView(){
    arView.automaticallyConfigureSession = false
    let configuration = ARWorldTrackingConfiguration()
    configuration.planeDetection = [.horizontal, .vertical]
    configuration.environmentTexturing = .automatic
    arView.session.run(configuration)
 }

 //object placement
 
@objc
func handleTap(recognizer: UITapGestureRecognizer){
    let location = recognizer.location(in:arView)
    
    let results = arView.raycast(from: location, allowing: .estimatedPlane, alignment: 
 .horizontal)
    
    if let firstResult = results.first {
        let anchor = ARAnchor(name: "fender_stratocaster", transform: 
firstResult.worldTransform)
        arView.session.add(anchor: anchor)
    } else {
        print("Object placement failed - couldn't find surface.")
    }
}

func placeObject(named entityName: String, for anchor: ARAnchor)  {
    let entity = try! ModelEntity.loadModel(named: entityName)
    
    entity.generateCollisionShapes(recursive: true)
    arView.installGestures([.rotation, .translation], for: entity)
    
    
    let anchorEntity = AnchorEntity(anchor: anchor)
    AnchorEntity.addChild(entity)
    arView.scene.addAnchor(anchorEntity)
    
    
    }
}
extension ViewController: ARSessionDelegate {
func session( session: ARSession, didAdd anchors: [ARAnchor]) {
for anchor in anchors {
    if let anchorName = anchor.name, anchorName == "fender_stratocaster" {
        placeObject(named: anchorName, for: anchor)
    }  }
}
}

【问题讨论】：

标签： swift xcode augmented-reality arkit realitykit

【解决方案1】：

如我所见，问题出在这一行（而且看起来像是印刷错误）：

AnchorEntity.addChild(entity)        // type

但是，您肯定需要改用以下行：

anchorEntity.addChild(entity)        // instance of class

因此您的版本无法成功运行，因为 AnchorEntity 是一种类型，而不是类实例。

关于类对象

当您创建一个实例时，您会初始化一个类（这里，使用其默认属性：World(0,0,0)）：

let anchorEntity = AnchorEntity()    // instantiating

如果你不打算使用实例，你可以使用一个类本身：

AnchorEntity().addChild(entity)      // class

【讨论】：