[camera_avfoundation] iOS: Fix crash when enableAudio == false by correcting guard condition (#9949)

## Summary

This PR fixes an iOS crash that occurs when using the `camera` plugin with `enableAudio: false` and no `NSMicrophoneUsageDescription` in `Info.plist`.

**Root cause:**  
In `DefaultCamera.setUpCaptureSessionForAudioIfNeeded()`, the guard currently allows audio setup to proceed even when audio is disabled:

```swift
// current (buggy)
guard !mediaSettings.enableAudio || !isAudioSetup else { return }
```

This evaluates to `true` when `enableAudio == false`, so the audio setup runs regardless.

**Fix:** Require audio to be enabled **and** not already set up before proceeding:

```swift
// fixed
guard mediaSettings.enableAudio && !isAudioSetup else { return }
```

This aligns behavior with the intended logic (“don’t set up audio twice or when audio is disabled”) and prevents the crash path on iOS when the microphone usage description is absent.

- **Affected file:**  
  `camera_avfoundation/ios/camera_avfoundation/Sources/camera_avfoundation/DefaultCamera.swift`

- **Proposed correction commit:**  
  juliendelarbre@0635db4

- **Related Flutter issue & discussion:**  
  [flutter/flutter#174702 (comment)](flutter/flutter#174702 (comment))

---

## Before / After

**Before (buggy):** audio setup runs when `enableAudio == false`, causing a crash on iOS if `NSMicrophoneUsageDescription` is missing.

**After (fixed):** audio setup is skipped when `enableAudio == false`; no crash, behavior matches API expectations.

---

## Reproduction steps

1. Create a Flutter project targeting iOS.  
2. Ensure `ios/Runner/Info.plist` does **not** contain `NSMicrophoneUsageDescription`.  
3. Initialize `CameraController` with `enableAudio: false`.  
4. Call `startVideoRecording()`.  
5. Observe crash (on current main); with this PR applied, no crash.

---

## Linked Issues

Fixes flutter/flutter#174702

---

## Documentation

No API changes; behavior now matches the documented intent. (Optional: add a short inline comment elaborating that audio setup is skipped when `enableAudio == false`.)

---

## Pre-Review Checklist

Author: juliendelarbre

packages/camera/camera_avfoundation/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.9.22+1
+
+* Fixes crash on iOS when `enableAudio` is false.
+
 ## 0.9.22
 
 * Adds lensType in the PlatformCameraDescription

packages/camera/camera_avfoundation/example/ios/RunnerTests/CameraSettingsTests.swift

@@ -16,7 +16,6 @@ private let testResolutionPreset = FCPPlatformResolutionPreset.medium
 private let testFramesPerSecond = 15
 private let testVideoBitrate = 200000
 private let testAudioBitrate = 32000
-private let testEnableAudio = true
 
 private final class TestMediaSettingsAVWrapper: FLTCamMediaSettingsAVWrapper {
   let lockExpectation: XCTestExpectation
@@ -28,14 +27,15 @@ private final class TestMediaSettingsAVWrapper: FLTCamMediaSettingsAVWrapper {
   let audioSettingsExpectation: XCTestExpectation
   let videoSettingsExpectation: XCTestExpectation
 
-  init(test: XCTestCase) {
+  init(test: XCTestCase, expectAudio: Bool) {
     lockExpectation = test.expectation(description: "lockExpectation")
     unlockExpectation = test.expectation(description: "unlockExpectation")
     minFrameDurationExpectation = test.expectation(description: "minFrameDurationExpectation")
     maxFrameDurationExpectation = test.expectation(description: "maxFrameDurationExpectation")
     beginConfigurationExpectation = test.expectation(description: "beginConfigurationExpectation")
     commitConfigurationExpectation = test.expectation(description: "commitConfigurationExpectation")
     audioSettingsExpectation = test.expectation(description: "audioSettingsExpectation")
+    audioSettingsExpectation.isInverted = !expectAudio
     videoSettingsExpectation = test.expectation(description: "videoSettingsExpectation")
   }
 
@@ -114,14 +114,15 @@ private final class TestMediaSettingsAVWrapper: FLTCamMediaSettingsAVWrapper {
 
 final class CameraSettingsTests: XCTestCase {
   func testSettings_shouldPassConfigurationToCameraDeviceAndWriter() {
+    let enableAudio: Bool = true
     let settings = FCPPlatformMediaSettings.make(
       with: testResolutionPreset,
       framesPerSecond: NSNumber(value: testFramesPerSecond),
       videoBitrate: NSNumber(value: testVideoBitrate),
       audioBitrate: NSNumber(value: testAudioBitrate),
-      enableAudio: testEnableAudio
+      enableAudio: enableAudio
     )
-    let injectedWrapper = TestMediaSettingsAVWrapper(test: self)
+    let injectedWrapper = TestMediaSettingsAVWrapper(test: self, expectAudio: enableAudio)
 
     let configuration = CameraTestUtils.createTestCameraConfiguration()
     configuration.mediaSettingsWrapper = injectedWrapper
@@ -173,7 +174,7 @@ final class CameraSettingsTests: XCTestCase {
       framesPerSecond: NSNumber(value: testFramesPerSecond),
       videoBitrate: NSNumber(value: testVideoBitrate),
       audioBitrate: NSNumber(value: testAudioBitrate),
-      enableAudio: testEnableAudio
+      enableAudio: false
     )
     var resultValue: NSNumber?
     camera.createCameraOnSessionQueue(
@@ -195,7 +196,7 @@ final class CameraSettingsTests: XCTestCase {
       framesPerSecond: NSNumber(value: 60),
       videoBitrate: NSNumber(value: testVideoBitrate),
       audioBitrate: NSNumber(value: testAudioBitrate),
-      enableAudio: testEnableAudio
+      enableAudio: false
     )
 
     let configuration = CameraTestUtils.createTestCameraConfiguration()
@@ -206,4 +207,97 @@ final class CameraSettingsTests: XCTestCase {
     XCTAssertLessThanOrEqual(range.minFrameRate, 60)
     XCTAssertGreaterThanOrEqual(range.maxFrameRate, 60)
   }
+  func test_setUpCaptureSessionForAudioIfNeeded_skipsAudioSession_whenAudioDisabled() {
+    let settings = FCPPlatformMediaSettings.make(
+      with: testResolutionPreset,
+      framesPerSecond: NSNumber(value: testFramesPerSecond),
+      videoBitrate: NSNumber(value: testVideoBitrate),
+      audioBitrate: NSNumber(value: testAudioBitrate),
+      enableAudio: false
+    )
+
+    let wrapper = TestMediaSettingsAVWrapper(test: self, expectAudio: false)
+    let mockAudioSession = MockCaptureSession()
+
+    let configuration = CameraTestUtils.createTestCameraConfiguration()
+    configuration.mediaSettingsWrapper = wrapper
+    configuration.mediaSettings = settings
+    configuration.audioCaptureSession = mockAudioSession
+    let camera = CameraTestUtils.createTestCamera(configuration)
+
+    wait(
+      for: [
+        wrapper.lockExpectation,
+        wrapper.beginConfigurationExpectation,
+        wrapper.minFrameDurationExpectation,
+        wrapper.maxFrameDurationExpectation,
+        wrapper.commitConfigurationExpectation,
+        wrapper.unlockExpectation,
+      ],
+      timeout: 1,
+      enforceOrder: true
+    )
+
+    camera.startVideoRecording(completion: { _ in }, messengerForStreaming: nil)
+
+    wait(
+      for: [
+        wrapper.audioSettingsExpectation,
+        wrapper.videoSettingsExpectation,
+      ],
+      timeout: 1
+    )
+
+    XCTAssertEqual(
+      mockAudioSession.addedAudioOutputCount, 0,
+      "Audio session should not receive AVCaptureAudioDataOutput when enableAudio is false"
+    )
+  }
+
+  func test_setUpCaptureSessionForAudioIfNeeded_addsAudioSession_whenAudioEnabled() {
+    let settings = FCPPlatformMediaSettings.make(
+      with: testResolutionPreset,
+      framesPerSecond: NSNumber(value: testFramesPerSecond),
+      videoBitrate: NSNumber(value: testVideoBitrate),
+      audioBitrate: NSNumber(value: testAudioBitrate),
+      enableAudio: true
+    )
+
+    let wrapper = TestMediaSettingsAVWrapper(test: self, expectAudio: true)
+    let mockAudioSession = MockCaptureSession()
+
+    let configuration = CameraTestUtils.createTestCameraConfiguration()
+    configuration.mediaSettingsWrapper = wrapper
+    configuration.mediaSettings = settings
+    configuration.audioCaptureSession = mockAudioSession
+    let camera = CameraTestUtils.createTestCamera(configuration)
+
+    wait(
+      for: [
+        wrapper.lockExpectation,
+        wrapper.beginConfigurationExpectation,
+        wrapper.minFrameDurationExpectation,
+        wrapper.maxFrameDurationExpectation,
+        wrapper.commitConfigurationExpectation,
+        wrapper.unlockExpectation,
+      ],
+      timeout: 1,
+      enforceOrder: true
+    )
+
+    camera.startVideoRecording(completion: { _ in }, messengerForStreaming: nil)
+
+    wait(
+      for: [
+        wrapper.audioSettingsExpectation,
+        wrapper.videoSettingsExpectation,
+      ],
+      timeout: 1
+    )
+
+    XCTAssertGreaterThan(
+      mockAudioSession.addedAudioOutputCount, 0,
+      "Audio session should receive AVCaptureAudioDataOutput when enableAudio is true"
+    )
+  }
 }

packages/camera/camera_avfoundation/example/ios/RunnerTests/Mocks/MockCaptureSession.swift

@@ -22,6 +22,9 @@ final class MockCaptureSession: NSObject, FLTCaptureSession {
   var _sessionPreset = AVCaptureSession.Preset.high
   var inputs = [AVCaptureInput]()
   var outputs = [AVCaptureOutput]()
+
+  private(set) var addedAudioOutputCount: Int = 0
+
   var automaticallyConfiguresApplicationAudioSession = false
 
   var sessionPreset: AVCaptureSession.Preset {
@@ -61,7 +64,12 @@ final class MockCaptureSession: NSObject, FLTCaptureSession {
 
   func addInput(_: FLTCaptureInput) {}
 
-  func addOutput(_: AVCaptureOutput) {}
+  func addOutput(_ output: AVCaptureOutput) {
+
+    if output is AVCaptureAudioDataOutput {
+      addedAudioOutputCount += 1
+    }
+  }
 
   func removeInput(_: FLTCaptureInput) {}
 

packages/camera/camera_avfoundation/ios/camera_avfoundation/Sources/camera_avfoundation/DefaultCamera.swift

@@ -340,7 +340,7 @@ final class DefaultCamera: NSObject, Camera {
 
   func setUpCaptureSessionForAudioIfNeeded() {
     // Don't setup audio twice or we will lose the audio.
-    guard !mediaSettings.enableAudio || !isAudioSetup else { return }
+    guard mediaSettings.enableAudio && !isAudioSetup else { return }
 
     let audioDevice = audioCaptureDeviceFactory()
     do {

packages/camera/camera_avfoundation/pubspec.yaml

@@ -2,7 +2,7 @@ name: camera_avfoundation
 description: iOS implementation of the camera plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_avfoundation
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.9.22
+version: 0.9.22+1
 
 environment:
   sdk: ^3.9.0