场景工具包渲染器上的错误访问崩溃答案

【问题标题】：Bad access crash on scene kit renderer场景工具包渲染器上的错误访问崩溃
【发布时间】：2019-12-03 02:51:01
【问题描述】：

崩溃：

com.apple.scenekit.scnview-renderer (34)：EXC_BAD_ACCESS（代码=1，地址=0x68）

在按下按钮时尝试删除节点时，我不断遇到错误的访问崩溃。在某些情况下，为了重现崩溃，车辆必须生成并删除 2 或 3 次。我利用 removeFromParentNode 函数，并将 SCNNode 的全局变量设置为 nil。

已尝试在 main 上调度队列。
尝试了异常和符号断点。
尝试深入了解分配/僵尸工具，但未发现明显的内存泄漏/释放。内存已正确释放。
尝试使用 SCNTransaction 隐藏 UI。

添加节点功能：


    @IBAction func addCarToSceneView(_ sender: UITapGestureRecognizer) {

            if self.sharedCarNode == nil {
            //if there is no car spawned, activate haptic feedback.
            self.feedbackGenerator = UIImpactFeedbackGenerator()
            self.feedbackGenerator?.impactOccurred()

            //Get tap location
            let tapLocation = sender.location(in: self.sceneView)
            let hitTestResults = self.sceneView.hitTest(tapLocation, types: .existingPlane)

            //Get first hit from tap location and grab where plane and node intersect
            guard let firstHit = hitTestResults.first else {return}
            let translation = firstHit.worldTransform.translation
            let x = translation.x
            let y = translation.y
            let z = translation.z

            //Initiate the scene from file
            guard let carScene = SCNScene(named: "Avent.scn", inDirectory: "art.scnassets/Aventador", options: nil),

            let carNode = carScene.rootNode.childNode(withName: "Car", recursively: true) else { return }

            carNode.position = SCNVector3(x, y + 4, z - 10)

            //Drop car animation to detected plane
            let originalCarPosition = SCNVector3Make(x, y, z)

            let dropCar = SCNAction.move(to: originalCarPosition, duration: 0.5)
            carNode.runAction(dropCar)

            self.positionForRotation = originalCarPosition

            self.sceneView.scene.rootNode.addChildNode(carNode)

            self.sharedCarNode = carNode

            self.rotateButton.isEnabled = true

            }

            //Hide all Planes in view once a car is spawned
            for plane in self.planes {
                plane.isHidden = true
                }

        }

删除汽车功能：

@IBAction func deletePressed(_ sender: UIButton) {
        self.sharedCarNode?.removeFromParentNode()
        self.sharedCarNode = nil
        for plane in self.planes {
            plane.isHidden = false
        }
        self.scaleFactor.text = "Scale: 0%"
    }

错误信息：

Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]
PID: 1685, TID: 396634, Thread name: com.apple.CoreMotion.MotionThread, Queue name: com.apple.root.default-qos.overcommit, QoS: 0
Backtrace:
4   libobjc.A.dylib                     0x000000020f3cf6f4 <redacted> + 56
5   CoreMotion                          0x0000000215b49d9c CoreMotion + 294300
6   CoreMotion                          0x0000000215b4a2cc CoreMotion + 295628
7   CoreMotion                          0x0000000215b4a1dc CoreMotion + 295388
8   CoreMotion                          0x0000000215b7801c CoreMotion + 483356
9   CoreMotion                          0x0000000215b78060 CoreMotion + 483424
10  CoreFoundation                      0x000000021015e27c <redacted> + 28
11  CoreFoundation                      0x000000021015db64 <redacted> + 276
12  CoreFoundation                      0x0000000210158e58 <redacted> + 2276
13  CoreFoundation                      0x0000000210158254 CFRunLoopRunSpecific + 452
14  CoreFoundation                      0x0000000210158f88 CFRunLoopRun + 84
15  CoreMotion                          0x0000000215b779f4 CoreMotion + 481780
16  libsystem_pthread.dylib             0x000000020fdd6908 <redacted> + 132
17  libsystem_pthread.dylib             0x000000020fdd6864 _pthread_start + 48
18  libsystem_pthread.dylib             0x000000020fddedcc thread_start + 4
2019-07-24 17:29:25.746570-0400 Portal[1685:396634] [reports] Main Thread Checker: UI API called on a background thread: -[UIApplication applicationState]
PID: 1685, TID: 396634, Thread name: com.apple.CoreMotion.MotionThread, Queue name: com.apple.root.default-qos.overcommit, QoS: 0
Backtrace:
4   libobjc.A.dylib                     0x000000020f3cf6f4 <redacted> + 56
5   CoreMotion                          0x0000000215b49d9c CoreMotion + 294300
6   CoreMotion                          0x0000000215b4a2cc CoreMotion + 295628
7   CoreMotion                          0x0000000215b4a1dc CoreMotion + 295388
8   CoreMotion                          0x0000000215b7801c CoreMotion + 483356
9   CoreMotion                          0x0000000215b78060 CoreMotion + 483424
10  CoreFoundation                      0x000000021015e27c <redacted> + 28
11  CoreFoundation                      0x000000021015db64 <redacted> + 276
12  CoreFoundation                      0x0000000210158e58 <redacted> + 2276
13  CoreFoundation                      0x0000000210158254 CFRunLoopRunSpecific + 452
14  CoreFoundation                      0x0000000210158f88 CFRunLoopRun + 84
15  CoreMotion                          0x0000000215b779f4 CoreMotion + 481780
16  libsystem_pthread.dylib             0x000000020fdd6908 <redacted> + 132
17  libsystem_pthread.dylib             0x000000020fdd6864 _pthread_start + 48
18  libsystem_pthread.dylib             0x000000020fddedcc thread_start + 4
2019-07-24 17:29:48.348816-0400 Portal[1685:396639] [Graphics] UIColor created with component values far outside the expected range. Set a breakpoint on UIColorBreakForOutOfRangeColorComponents to debug. This message will only be logged once.

【问题讨论】：

标签： ios swift arkit

【解决方案1】：

当渲染器委托方法更新不同线程中的节点时，尝试在主线程（由IBAction 发出）中隐藏/取消隐藏SCNNodes 时，我遇到了类似的问题。您的源代码没有显示节点如何随着时间/渲染器更新功能而变化。

例如：

@IBAction func toggleAnchorGrid(_ sender: UIBarButtonItem) 
   {

    showGrid = !showGrid
    for node in self.grids{
         node.isHidden = self.showGrid ? false : true
    }


//MARK: - SceneView renderer delegate methods...

func renderer(_ renderer: SCNSceneRenderer, didUpdate node: SCNNode, for anchor: ARAnchor) {

    DispatchQueue.main.async {
        if self.showGrid {
            if let foundGrid = self.grids.filter({ $0.anchor.identifier == anchor.identifier }).first {
                foundGrid.update(anchor: anchor as! ARPlaneAnchor)
            }
        }
    }
......

【讨论】：