SwiftUI – 将数据从 SwiftUIView 传递到 SceneKit

Question

目标： 使用 Scenekit (UIViewRepresentable) 控制 SwiftUI 视图的 SwiftUI 切换按钮

//显示fps和计时信息等统计信息

我做了什么： 这是 UIViewRepresentable ScenekitView

import SwiftUI
import SceneKit

struct ScenekitView : UIViewRepresentable {
    let scene = SCNScene(named: "art.scnassets/ship.scn")!

    func makeUIView(context: Context) -> SCNView {
        // create and add a camera to the scene
        let cameraNode = SCNNode()
        cameraNode.camera = SCNCamera()
        scene.rootNode.addChildNode(cameraNode)

        // place the camera
        cameraNode.position = SCNVector3(x: 0, y: 0, z: 15)

        // create and add a light to the scene
        let lightNode = SCNNode()
        lightNode.light = SCNLight()
        lightNode.light!.type = .omni
        lightNode.position = SCNVector3(x: 0, y: 10, z: 10)
        scene.rootNode.addChildNode(lightNode)

        // create and add an ambient light to the scene
        let ambientLightNode = SCNNode()
        ambientLightNode.light = SCNLight()
        ambientLightNode.light!.type = .ambient
        ambientLightNode.light!.color = UIColor.darkGray
        scene.rootNode.addChildNode(ambientLightNode)

        // retrieve the ship node
        let ship = scene.rootNode.childNode(withName: "ship", recursively: true)!

        // animate the 3d object
        ship.runAction(SCNAction.repeatForever(SCNAction.rotateBy(x: 0, y: 2, z: 0, duration: 1)))

        // retrieve the SCNView
        let scnView = SCNView()
        return scnView
    }

    func updateUIView(_ scnView: SCNView, context: Context) {
        scnView.scene = scene

        // allows the user to manipulate the camera
        scnView.allowsCameraControl = true

        // show statistics such as fps and timing information

        scnView.showsStatistics = true

        // configure the view
        scnView.backgroundColor = UIColor.black

 }

}
struct ScenekitView_Previews: PreviewProvider {
    static var previews: some View {
        ScenekitView()
    }
}

这是控制 Scenekit 的菜单

import SwiftUI


struct Menu: View {

 @State var showstats = false


    var body: some View {

        HStack {

        Form {
            Toggle(isOn:) {
               Text("Stats")
            }
        }
        .frame(width: 200.0)

            Spacer()
    }
  }
 }
struct Menu_Previews: PreviewProvider {
    static var previews: some View {
        Menu()
    }
}

这是主场景，菜单位于 Scenekit 之上：

import SwiftUI

struct MainView: View {
    var body: some View {

        ZStack {
        ScenekitView()
        Menu()
        }


    }
}

问题：如何将数据从 ScenekitView 传递到菜单，以便切换和显示/隐藏统计信息？

我尝试了 ObservableObject 但无法使其工作。还查看了其他 SO 线程，但没有一个对我有用。

非常感谢任何帮助！

向大家干杯

Answer 1

更新：2020 年 3 月 11 日。

要将数据传递给 updateNSView(_:context:) 或 updateUIView(_:context:) 实例方法，您需要创建 @State 和 @Binding 属性。

使用以下代码了解如何操作：

我已经为 macOS 编写了这段代码，但您可以轻松地为 iOS 更改它：

import SwiftUI
import SceneKit

struct ContentView: View {

    @State var stats: Bool = true

    var body: some View {
        HStack {
            ScenekitView(showStats: $stats)
            VStack {
                Button(action: {
                    self.stats.toggle()
                }, label: {
                    Text(self.stats ? "ON" : "OFF")
                })
            }
            .frame(width: 150.0)
        }
    }
}

struct ScenekitView: NSViewRepresentable {

    @Binding var showStats: Bool
    let sceneView = SCNView(frame: .zero)
    let scene = SCNScene(named: "art.scnassets/ship.scn")!

    func scnScene(stat: Bool, context: Context) -> SCNView {
        sceneView.scene = scene
        sceneView.showsStatistics = stat
        return sceneView
    }

    func makeNSView(context: Context) -> SCNView {
        scnScene(stat: true, context: context)
    }

    func updateNSView(_ uiView: SCNView, context: Context) {
        uiView.allowsCameraControl = true
        uiView.backgroundColor = NSColor.black
        uiView.showsStatistics = showStats        
    }
}

此外，您还可以使用 Coordinator 对象和 delegate 到此协调器，以使用 control 属性切换对象，并在 renderer() 方法内以 60 fps 更新任何内容（例如）。

在这种情况下您不需要使用updateNSView() 或updateUIView() 方法：

struct ScenekitView: NSViewRepresentable {

    @Binding var showStats: Bool
    let sceneView = SCNView(frame: .zero)
    let scene = SCNScene(named: "art.scnassets/ship.scn")!

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    final class Coordinator: NSObject, SCNSceneRendererDelegate {
        var control: ScenekitView

        init(_ control: ScenekitView) {
            self.control = control
        }

        func renderer(_ renderer: SCNSceneRenderer,
               updateAtTime time: TimeInterval) {

            control.sceneView.showsStatistics = control.showStats

            for i in 0...255 {
                control.sceneView.backgroundColor = NSColor(
                                  red: CGFloat(arc4random_uniform(UInt32(i))),
                                green: CGFloat(arc4random_uniform(UInt32(i))),
                                 blue: CGFloat(arc4random_uniform(UInt32(i))),
                                alpha: 1.0)
            }
        }
    }

    func scnScene(stat: Bool, context: Context) -> SCNView {
        sceneView.scene = scene
        sceneView.showsStatistics = stat
        sceneView.delegate = context.coordinator
        return sceneView
    }

    func makeNSView(context: Context) -> SCNView {
        scnScene(stat: true, context: context)
    }

    func updateNSView(_ uiView: SCNView, context: Context) { }
}