flutter · auto-submit · Jun 16, 2025 · Feb 27, 2025 · Feb 27, 2025 · Feb 27, 2025
@@ -1,3 +1,8 @@
+## 0.9.19+3
+
+* Fixes race condition when starting image stream.
+
+
 ## 0.9.19+2
 
 * Adds the `Camera` Swift protocol.

@@ -25,7 +25,7 @@
 		978D90B42D5F630300CD817E /* StreamingTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 978D90B32D5F630300CD817E /* StreamingTests.swift */; };
 		97922B0D2D6380C300A9B4CF /* SampleBufferTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 97922B0C2D6380C300A9B4CF /* SampleBufferTests.swift */; };
 		979B3DFB2D5B6BC7009BDE1A /* ExceptionCatcher.m in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFA2D5B6BC7009BDE1A /* ExceptionCatcher.m */; };
-		979B3DFE2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFD2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift */; };
+		979B3DFE2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFD2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift */; };
 		979B3E002D5B9E6C009BDE1A /* CameraMethodChannelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3DFF2D5B9E6C009BDE1A /* CameraMethodChannelTests.swift */; };
 		979B3E022D5BA48F009BDE1A /* CameraOrientationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 979B3E012D5BA48F009BDE1A /* CameraOrientationTests.swift */; };
 		97BD4A0E2D5CC5AE00F857D5 /* CameraSettingsTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 97BD4A0D2D5CC5AE00F857D5 /* CameraSettingsTests.swift */; };
@@ -114,7 +114,7 @@
 		979B3DF92D5B6BA2009BDE1A /* ExceptionCatcher.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ExceptionCatcher.h; sourceTree = "<group>"; };
 		979B3DFA2D5B6BC7009BDE1A /* ExceptionCatcher.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = ExceptionCatcher.m; sourceTree = "<group>"; };
 		979B3DFC2D5B985B009BDE1A /* RunnerTests-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "RunnerTests-Bridging-Header.h"; sourceTree = "<group>"; };
-		979B3DFD2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraCaptureSessionQueueRaceConditionTests.swift; sourceTree = "<group>"; };
+		979B3DFD2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraInitRaceConditionsTests.swift; sourceTree = "<group>"; };
 		979B3DFF2D5B9E6C009BDE1A /* CameraMethodChannelTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraMethodChannelTests.swift; sourceTree = "<group>"; };
 		979B3E012D5BA48F009BDE1A /* CameraOrientationTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraOrientationTests.swift; sourceTree = "<group>"; };
 		97BD4A0D2D5CC5AE00F857D5 /* CameraSettingsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CameraSettingsTests.swift; sourceTree = "<group>"; };
@@ -191,7 +191,7 @@
 				979B3DF92D5B6BA2009BDE1A /* ExceptionCatcher.h */,
 				979B3DFA2D5B6BC7009BDE1A /* ExceptionCatcher.m */,
 				979B3DFC2D5B985B009BDE1A /* RunnerTests-Bridging-Header.h */,
-				979B3DFD2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift */,
+				979B3DFD2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift */,
 				979B3DFF2D5B9E6C009BDE1A /* CameraMethodChannelTests.swift */,
 				979B3E012D5BA48F009BDE1A /* CameraOrientationTests.swift */,
 				97BD4A0D2D5CC5AE00F857D5 /* CameraSettingsTests.swift */,
@@ -552,7 +552,7 @@
 				E1ABED6D2D94392700AED9CC /* MockAssetWriterInput.swift in Sources */,
 				977A25242D5A511600931E34 /* CameraPermissionTests.swift in Sources */,
 				970ADABE2D6740A900EFDCD9 /* MockWritableData.swift in Sources */,
-				979B3DFE2D5B985B009BDE1A /* CameraCaptureSessionQueueRaceConditionTests.swift in Sources */,
+				979B3DFE2D5B985B009BDE1A /* CameraInitRaceConditionsTests.swift in Sources */,
 				E142F13A2D85940600824824 /* MockCapturePhotoOutput.swift in Sources */,
 				E12C4FF82D68E85500515E70 /* MockFLTCameraPermissionManager.swift in Sources */,
 				97922B0D2D6380C300A9B4CF /* SampleBufferTests.swift in Sources */,

@@ -11,7 +11,7 @@ import XCTest
   import camera_avfoundation_objc
 #endif
 
-final class CameraCaptureSessionQueueRaceConditionTests: XCTestCase {
+final class CameraInitRaceConditionsTests: XCTestCase {
   private func createCameraPlugin() -> (CameraPlugin, DispatchQueue) {
     let captureSessionQueue = DispatchQueue(label: "io.flutter.camera.captureSessionQueue")
 
@@ -62,4 +62,36 @@ final class CameraCaptureSessionQueueRaceConditionTests: XCTestCase {
     XCTAssertNotNil(
       captureSessionQueue, "captureSessionQueue must not be nil after create method.")
   }
+
+  func testFlutterChannelInitializedWhenStartingImageStream() {
+    let (cameraPlugin, _captureSessionQueue) = createCameraPlugin()
+    let createExpectation = expectation(description: "create's result block must be called")
+
+    cameraPlugin.createCameraOnSessionQueue(
+      withName: "acamera",
+      settings: FCPPlatformMediaSettings.make(
+        with: .medium,
+        framesPerSecond: nil,
+        videoBitrate: nil,
+        audioBitrate: nil,
+        enableAudio: true
+      )
+    ) { result, error in
+      createExpectation.fulfill()
+    }
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    // Start stream and wait for its completion.
+    let startStreamExpectation = expectation(
+      description: "startImageStream's result block must be called")
+    cameraPlugin.startImageStream(completion: {
+      _ in
+      startStreamExpectation.fulfill()
+    })
+
+    waitForExpectations(timeout: 30, handler: nil)
+    XCTAssertEqual(cameraPlugin.camera?.isStreamingImages, true)
+  }
+
 }
@@ -261,8 +261,9 @@ final class CameraPluginDelegatingMethodTests: XCTestCase {
     let expectation = expectation(description: "Call completed")
 
     var startImageStreamCalled = false
-    mockCamera.startImageStreamStub = { _ in
+    mockCamera.startImageStreamStub = { messenger, completion in
       startImageStreamCalled = true
+      completion(nil)
     }
 
     cameraPlugin.startImageStream { error in

@@ -39,7 +39,7 @@ final class MockCamera: NSObject, Camera {
   var pausePreviewStub: (() -> Void)?
   var resumePreviewStub: (() -> Void)?
   var setDescriptionWhileRecordingStub: ((String, ((FlutterError?) -> Void)?) -> Void)?
-  var startImageStreamStub: ((FlutterBinaryMessenger) -> Void)?
+  var startImageStreamStub: ((FlutterBinaryMessenger, (FlutterError?) -> Void) -> Void)?
   var stopImageStreamStub: (() -> Void)?
 
   var dartAPI: FCPCameraEventApi? {
@@ -63,6 +63,7 @@ final class MockCamera: NSObject, Camera {
   var videoFormat: FourCharCode = kCVPixelFormatType_32BGRA
 
   var isPreviewPaused: Bool = false
+  var isStreamingImages: Bool = false
 
   var minimumExposureOffset: CGFloat {
     return getMinimumExposureOffsetStub?() ?? 0
@@ -186,8 +187,11 @@ final class MockCamera: NSObject, Camera {
     setDescriptionWhileRecordingStub?(cameraName, completion)
   }
 
-  func startImageStream(with messenger: FlutterBinaryMessenger) {
-    startImageStreamStub?(messenger)
+  func startImageStream(
+    with messenger: FlutterBinaryMessenger,
+    completion: @escaping (FlutterError?) -> Void
+  ) {
+    startImageStreamStub?(messenger, completion)
   }
 
   func stopImageStream() {

@@ -52,14 +52,28 @@ final class StreamingTests: XCTestCase {
 
   func testExceedMaxStreamingPendingFramesCount() {
     let (camera, testAudioOutput, sampleBuffer, testAudioConnection) = createCamera()
+    let handlerMock = MockImageStreamHandler()
+
+    let finishStartStreamExpectation = expectation(
+      description: "Finish startStream")
+
+    let messenger = MockFlutterBinaryMessenger()
+    camera.startImageStream(
+      with: messenger, imageStreamHandler: handlerMock,
+      completion: {
+        _ in
+        finishStartStreamExpectation.fulfill()
+      })
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    // Setup mocked event sink after the stream starts
     let streamingExpectation = expectation(
       description: "Must not call handler over maxStreamingPendingFramesCount")
-    let handlerMock = MockImageStreamHandler()
+
     handlerMock.eventSinkStub = { event in
       streamingExpectation.fulfill()
     }
-    let messenger = MockFlutterBinaryMessenger()
-    camera.startImageStream(with: messenger, imageStreamHandler: handlerMock)
 
     waitForQueueRoundTrip(with: DispatchQueue.main)
     XCTAssertEqual(camera.isStreamingImages, true)
@@ -74,14 +88,27 @@ final class StreamingTests: XCTestCase {
 
   func testReceivedImageStreamData() {
     let (camera, testAudioOutput, sampleBuffer, testAudioConnection) = createCamera()
+    let handlerMock = MockImageStreamHandler()
+
+    let finishStartStreamExpectation = expectation(
+      description: "Finish startStream")
+
+    let messenger = MockFlutterBinaryMessenger()
+    camera.startImageStream(
+      with: messenger, imageStreamHandler: handlerMock,
+      completion: {
+        _ in
+        finishStartStreamExpectation.fulfill()
+      })
+
+    waitForExpectations(timeout: 30, handler: nil)
+
+    // Setup mocked event sink after the stream starts
     let streamingExpectation = expectation(
       description: "Must be able to call the handler again when receivedImageStreamData is called")
-    let handlerMock = MockImageStreamHandler()
     handlerMock.eventSinkStub = { event in
       streamingExpectation.fulfill()
     }
-    let messenger = MockFlutterBinaryMessenger()
-    camera.startImageStream(with: messenger, imageStreamHandler: handlerMock)
 
     waitForQueueRoundTrip(with: DispatchQueue.main)
     XCTAssertEqual(camera.isStreamingImages, true)

@@ -25,6 +25,7 @@ protocol Camera: FlutterTexture, AVCaptureVideoDataOutputSampleBufferDelegate,
   var videoFormat: FourCharCode { get set }
 
   var isPreviewPaused: Bool { get }
+  var isStreamingImages: Bool { get }
 
   var minimumAvailableZoomFactor: CGFloat { get }
   var maximumAvailableZoomFactor: CGFloat { get }
@@ -86,7 +87,8 @@ protocol Camera: FlutterTexture, AVCaptureVideoDataOutputSampleBufferDelegate,
     withCompletion: @escaping (_ error: FlutterError?) -> Void
   )
 
-  func startImageStream(with: FlutterBinaryMessenger)
+  func startImageStream(
+    with: FlutterBinaryMessenger, completion: @escaping (_ error: FlutterError?) -> Void)
   func stopImageStream()
 
   // Override to make `AVCaptureVideoDataOutputSampleBufferDelegate`/

@@ -309,9 +309,11 @@ extension CameraPlugin: FCPCameraApi {
 
   public func startImageStream(completion: @escaping (FlutterError?) -> Void) {
     captureSessionQueue.async { [weak self] in
-      guard let strongSelf = self else { return }
-      strongSelf.camera?.startImageStream(with: strongSelf.messenger)
-      completion(nil)
+      guard let strongSelf = self else {
+        completion(nil)
+        return
+      }
+      strongSelf.camera?.startImageStream(with: strongSelf.messenger, completion: completion)
     }
   }
 

@@ -306,7 +306,7 @@ - (void)captureToFileWithCompletion:(void (^)(NSString *_Nullable,
   NSString *path = [self getTemporaryFilePathWithExtension:extension
                                                  subfolder:@"pictures"
                                                     prefix:@"CAP_"
-                                                     error:error];
+                                                     error:&error];
   if (error) {
     completion(nil, FlutterErrorFromNSError(error));
     return;
@@ -362,7 +362,7 @@ - (AVCaptureVideoOrientation)getVideoOrientationForDeviceOrientation:
 - (NSString *)getTemporaryFilePathWithExtension:(NSString *)extension
                                       subfolder:(NSString *)subfolder
                                          prefix:(NSString *)prefix
-                                          error:(NSError *)error {
+                                          error:(NSError **)error {
   NSString *docDir =
       NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
   NSString *fileDir =
@@ -373,11 +373,11 @@ - (NSString *)getTemporaryFilePathWithExtension:(NSString *)extension
 
   NSFileManager *fm = [NSFileManager defaultManager];
   if (![fm fileExistsAtPath:fileDir]) {
-    [[NSFileManager defaultManager] createDirectoryAtPath:fileDir
-                              withIntermediateDirectories:true
-                                               attributes:nil
-                                                    error:&error];
-    if (error) {
+    BOOL success = [[NSFileManager defaultManager] createDirectoryAtPath:fileDir
+                                             withIntermediateDirectories:true
+                                                              attributes:nil
+                                                                   error:error];
+    if (!success) {
       return nil;
     }
   }
@@ -498,43 +498,50 @@ - (void)dealloc {
   [_motionManager stopAccelerometerUpdates];
 }
 
+/// Main logic to setup the video recording.
+- (void)setUpVideoRecordingWithCompletion:(void (^)(FlutterError *_Nullable))completion {
+  NSError *error;
+  _videoRecordingPath = [self getTemporaryFilePathWithExtension:@"mp4"
+                                                      subfolder:@"videos"
+                                                         prefix:@"REC_"
+                                                          error:&error];
+  if (error) {
+    completion(FlutterErrorFromNSError(error));
+    return;
+  }
+  if (![self setupWriterForPath:_videoRecordingPath]) {
+    completion([FlutterError errorWithCode:@"IOError" message:@"Setup Writer Failed" details:nil]);
+    return;
+  }
+  // startWriting should not be called in didOutputSampleBuffer where it can cause state
+  // in which _isRecording is YES but _videoWriter.status is AVAssetWriterStatusUnknown
+  // in stopVideoRecording if it is called after startVideoRecording but before
+  // didOutputSampleBuffer had chance to call startWriting and lag at start of video
+  // https://github.com/flutter/flutter/issues/132016
+  // https://github.com/flutter/flutter/issues/151319
+  [_videoWriter startWriting];
+  _isFirstVideoSample = YES;
+  _isRecording = YES;
+  _isRecordingPaused = NO;
+  _videoTimeOffset = CMTimeMake(0, 1);
+  _audioTimeOffset = CMTimeMake(0, 1);
+  _videoIsDisconnected = NO;
+  _audioIsDisconnected = NO;
+  completion(nil);
+}
+
 - (void)startVideoRecordingWithCompletion:(void (^)(FlutterError *_Nullable))completion
                     messengerForStreaming:(nullable NSObject<FlutterBinaryMessenger> *)messenger {
   if (!_isRecording) {
     if (messenger != nil) {
-      [self startImageStreamWithMessenger:messenger];
-    }
-
-    NSError *error;
-    _videoRecordingPath = [self getTemporaryFilePathWithExtension:@"mp4"
-                                                        subfolder:@"videos"
-                                                           prefix:@"REC_"
-                                                            error:error];
-    if (error) {
-      completion(FlutterErrorFromNSError(error));
-      return;
-    }
-    if (![self setupWriterForPath:_videoRecordingPath]) {
-      completion([FlutterError errorWithCode:@"IOError"
-                                     message:@"Setup Writer Failed"
-                                     details:nil]);
+      [self startImageStreamWithMessenger:messenger
+                               completion:^(FlutterError *_Nullable error) {
+                                 [self setUpVideoRecordingWithCompletion:completion];
+                               }];
       return;
     }
-    // startWriting should not be called in didOutputSampleBuffer where it can cause state
-    // in which _isRecording is YES but _videoWriter.status is AVAssetWriterStatusUnknown
-    // in stopVideoRecording if it is called after startVideoRecording but before
-    // didOutputSampleBuffer had chance to call startWriting and lag at start of video
-    // https://github.com/flutter/flutter/issues/132016
-    // https://github.com/flutter/flutter/issues/151319
-    [_videoWriter startWriting];
-    _isFirstVideoSample = YES;
-    _isRecording = YES;
-    _isRecordingPaused = NO;
-    _videoTimeOffset = CMTimeMake(0, 1);
-    _audioTimeOffset = CMTimeMake(0, 1);
-    _videoIsDisconnected = NO;
-    _audioIsDisconnected = NO;
-    completion(nil);
+
+    [self setUpVideoRecordingWithCompletion:completion];
   } else {
     completion([FlutterError errorWithCode:@"Error"
                                    message:@"Video is already recording"
@@ -831,14 +838,17 @@ - (void)setExposureOffset:(double)offset {
   [_captureDevice unlockForConfiguration];
 }
 
-- (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger {
+- (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger
+                           completion:(void (^)(FlutterError *))completion {
   [self startImageStreamWithMessenger:messenger
                    imageStreamHandler:[[FLTImageStreamHandler alloc]
-                                          initWithCaptureSessionQueue:_captureSessionQueue]];
+                                          initWithCaptureSessionQueue:_captureSessionQueue]
+                           completion:completion];
 }
 
 - (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messenger
-                   imageStreamHandler:(FLTImageStreamHandler *)imageStreamHandler {
+                   imageStreamHandler:(FLTImageStreamHandler *)imageStreamHandler
+                           completion:(void (^)(FlutterError *))completion {
   if (!_isStreamingImages) {
     id<FLTEventChannel> eventChannel = [FlutterEventChannel
         eventChannelWithName:@"plugins.flutter.io/camera_avfoundation/imageStream"
@@ -851,19 +861,27 @@ - (void)startImageStreamWithMessenger:(NSObject<FlutterBinaryMessenger> *)messen
     [threadSafeEventChannel setStreamHandler:_imageStreamHandler
                                   completion:^{
                                     typeof(self) strongSelf = weakSelf;
-                                    if (!strongSelf) return;
+                                    if (!strongSelf) {
+                                      completion(nil);
+                                      return;
+                                    }
 
                                     dispatch_async(strongSelf.captureSessionQueue, ^{
                                       // cannot use the outter strongSelf
                                       typeof(self) strongSelf = weakSelf;
-                                      if (!strongSelf) return;
+                                      if (!strongSelf) {
+                                        completion(nil);
+                                        return;
+                                      }
 
                                       strongSelf.isStreamingImages = YES;
                                       strongSelf.streamingPendingFramesCount = 0;
+                                      completion(nil);
                                     });
                                   }];
   } else {
     [self reportErrorMessage:@"Images from camera are already streaming!"];
+    completion(nil);
   }
 }