feat(shutdown): implement graceful shutdown for camera session

package/ios/Core/CameraSession+Configuration.swift

@@ -61,6 +61,12 @@ extension CameraSession {
 
     // Remove all outputs
     for output in captureSession.outputs {
+      if let metadataOutput = output as? AVCaptureMetadataOutput {
+        metadataOutput.setMetadataObjectsDelegate(nil, queue: nil)
+      }
+      if let videoOutput = output as? AVCaptureVideoDataOutput {
+        videoOutput.setSampleBufferDelegate(nil, queue: nil)
+      }
       captureSession.removeOutput(output)
     }
     photoOutput = nil

package/ios/Core/CameraSession.swift

@@ -83,6 +83,18 @@ final class CameraSession: NSObject, AVCaptureVideoDataOutputSampleBufferDelegat
     NotificationCenter.default.removeObserver(self,
                                               name: AVAudioSession.interruptionNotification,
                                               object: AVAudioSession.sharedInstance)
+    let cameraCaptureSession = captureSession
+    CameraQueues.cameraQueue.async {
+      if cameraCaptureSession.isRunning {
+        cameraCaptureSession.stopRunning()
+      }
+    }
+    let cameraAudioSession = audioCaptureSession
+    CameraQueues.audioQueue.async {
+      if cameraAudioSession.isRunning {
+        cameraAudioSession.stopRunning()
+      }
+    }
   }
 
   /**
@@ -108,11 +120,14 @@ final class CameraSession: NSObject, AVCaptureVideoDataOutputSampleBufferDelegat
    Any changes in here will be re-configured only if required, and under a lock (in this case, the serial cameraQueue DispatchQueue).
    The `configuration` object is a copy of the currently active configuration that can be modified by the caller in the lambda.
    */
-  func configure(_ lambda: @escaping (_ configuration: CameraConfiguration) throws -> Void) {
+  func configure(_ lambda: @escaping (_ configuration: CameraConfiguration) throws -> Void,
+                 completion: (() -> Void)? = nil) {
     initialize()
 
     VisionLogger.log(level: .info, message: "configure { ... }: Waiting for lock...")
 
+    let completionBlock = completion
+
     // Set up Camera (Video) Capture Session (on camera queue, acts like a lock)
     CameraQueues.cameraQueue.async {
       // Let caller configure a new configuration for the Camera.
@@ -121,10 +136,12 @@ final class CameraSession: NSObject, AVCaptureVideoDataOutputSampleBufferDelegat
         try lambda(config)
       } catch CameraConfiguration.AbortThrow.abort {
         // call has been aborted and changes shall be discarded
+        completionBlock?()
         return
       } catch {
         // another error occured, possibly while trying to parse enums
         self.onConfigureError(error)
+        completionBlock?()
         return
       }
       let difference = CameraConfiguration.Difference(between: self.configuration, and: config)
@@ -244,9 +261,25 @@ final class CameraSession: NSObject, AVCaptureVideoDataOutputSampleBufferDelegat
           }
         }
       }
+      completionBlock?()
     }
   }
 
+  /**
+   Gracefully stop streaming and tear down any active outputs. Completion executes on the camera queue.
+   */
+  func shutdown(completion: (() -> Void)? = nil) {
+    configure({ config in
+      config.photo = .disabled
+      config.video = .disabled
+      config.audio = .disabled
+      config.codeScanner = .disabled
+      config.enableLocation = false
+      config.torch = .off
+      config.isActive = false
+    }, completion: completion)
+  }
+
   /**
    Starts or stops the CaptureSession if needed (`isActive`)
    */
@@ -265,7 +298,7 @@ final class CameraSession: NSObject, AVCaptureVideoDataOutputSampleBufferDelegat
     }
   }
 
-  public final func captureOutput(_ captureOutput: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
+  final func captureOutput(_ captureOutput: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
     switch captureOutput {
     case is AVCaptureVideoDataOutput:
       onVideoFrame(sampleBuffer: sampleBuffer, orientation: connection.orientation, isMirrored: connection.isVideoMirrored)

package/ios/React/CameraView.swift

@@ -103,6 +103,7 @@ public final class CameraView: UIView, CameraSessionDelegate, PreviewViewDelegat
   var isMounted = false
   private var currentConfigureCall: DispatchTime?
   private let fpsSampleCollector = FpsSampleCollector()
+  private var didScheduleShutdown = false
 
   // CameraView+Zoom
   var pinchGestureRecognizer: UIPinchGestureRecognizer?
@@ -129,16 +130,22 @@ public final class CameraView: UIView, CameraSessionDelegate, PreviewViewDelegat
     super.willMove(toSuperview: newSuperview)
 
     if newSuperview != nil {
+      didScheduleShutdown = false
       fpsSampleCollector.start()
       if !isMounted {
         isMounted = true
         onViewReadyEvent?(nil)
       }
     } else {
+      shutdownCameraSession()
       fpsSampleCollector.stop()
     }
   }
 
+  deinit {
+    shutdownCameraSession()
+  }
+
   override public func layoutSubviews() {
     if let previewView {
       previewView.frame = frame
@@ -283,6 +290,31 @@ public final class CameraView: UIView, CameraSessionDelegate, PreviewViewDelegat
     UIApplication.shared.isIdleTimerDisabled = isActive
   }
 
+  private func shutdownCameraSession() {
+    if didScheduleShutdown {
+      return
+    }
+    didScheduleShutdown = true
+
+    UIApplication.shared.isIdleTimerDisabled = false
+
+    #if VISION_CAMERA_ENABLE_FRAME_PROCESSORS
+      frameProcessor = nil
+    #endif
+
+    let slowShutdownWarning = DispatchWorkItem {
+      VisionLogger.log(level: .warning, message: "CameraSession shutdown is still running after 2 seconds.")
+    }
+    CameraQueues.cameraQueue.asyncAfter(deadline: .now() + .seconds(2), execute: slowShutdownWarning)
+
+    cameraSession.shutdown { [weak self] in
+      slowShutdownWarning.cancel()
+      DispatchQueue.main.async {
+        self?.didScheduleShutdown = false
+      }
+    }
+  }
+
   func updatePreview() {
     if preview && previewView == nil {
       // Create PreviewView and add it