[image_picker] Prevent multiple active calls on iOS (#5272)

The image picker plugin's implementation doesn't currently handle multiple calls correctly due to the use of an ivar to track the response object; the original entry point handles that by cancelling earlier requests when new ones come in, but as we added more entry points we didn't replicate that logic. This adds it to all picker entry points. (Longer term, we should instead handle multiple concurrent calls, but this is consistent with historical behavior, and is better than having some `await`s on the Dart side never return as can happen now.)

The newer PHPicker code path not only didn't cancel, but used an ivar for the picker view controller, which in some cases could result in the same controller being presented multiple times, crashing the app (see referenced issue). While the new cancel calls will prevent that case from happening, to prevent anything similar from happening in the future this removes the ivar entirely, since we can just pass the controller to the necessary methods (as is already being done with the `UIImagePickerController` paths).

Fixes https://github.com/flutter/flutter/issues/108900

packages/image_picker/image_picker_ios/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.8.8+3
+
+* Fixes a possible crash when calling a picker method while another is waiting on permissions.
+
 ## 0.8.8+2
 
 * Adds pub topics to package metadata.

packages/image_picker/image_picker_ios/example/ios/RunnerTests/ImagePickerPluginTests.m

@@ -531,4 +531,83 @@
   [self waitForExpectationsWithTimeout:30 handler:nil];
 }
 
+- (void)testPickMultiImageDuplicateCallCancels API_AVAILABLE(ios(14)) {
+  id mockPhotoLibrary = OCMClassMock([PHPhotoLibrary class]);
+  OCMStub([mockPhotoLibrary authorizationStatusForAccessLevel:PHAccessLevelReadWrite])
+      .andReturn(PHAuthorizationStatusNotDetermined);
+  OCMExpect([mockPhotoLibrary requestAuthorizationForAccessLevel:PHAccessLevelReadWrite
+                                                         handler:OCMOCK_ANY]);
+
+  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];
+
+  XCTestExpectation *firstCallExpectation = [self expectationWithDescription:@"first call"];
+  [plugin pickMultiImageWithMaxSize:[FLTMaxSize makeWithWidth:@100 height:@100]
+                            quality:nil
+                       fullMetadata:@YES
+                         completion:^(NSArray<NSString *> *result, FlutterError *error) {
+                           XCTAssertNotNil(error);
+                           XCTAssertEqualObjects(error.code, @"multiple_request");
+                           [firstCallExpectation fulfill];
+                         }];
+  [plugin pickMultiImageWithMaxSize:[FLTMaxSize makeWithWidth:@100 height:@100]
+                            quality:nil
+                       fullMetadata:@YES
+                         completion:^(NSArray<NSString *> *result, FlutterError *error){
+                         }];
+  [self waitForExpectationsWithTimeout:30 handler:nil];
+}
+
+- (void)testPickMediaDuplicateCallCancels API_AVAILABLE(ios(14)) {
+  id mockPhotoLibrary = OCMClassMock([PHPhotoLibrary class]);
+  OCMStub([mockPhotoLibrary authorizationStatusForAccessLevel:PHAccessLevelReadWrite])
+      .andReturn(PHAuthorizationStatusNotDetermined);
+  OCMExpect([mockPhotoLibrary requestAuthorizationForAccessLevel:PHAccessLevelReadWrite
+                                                         handler:OCMOCK_ANY]);
+
+  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];
+
+  FLTMediaSelectionOptions *options =
+      [FLTMediaSelectionOptions makeWithMaxSize:[FLTMaxSize makeWithWidth:@(100) height:@(200)]
+                                   imageQuality:@(50)
+                            requestFullMetadata:@YES
+                                  allowMultiple:@YES];
+  XCTestExpectation *firstCallExpectation = [self expectationWithDescription:@"first call"];
+  [plugin pickMediaWithMediaSelectionOptions:options
+                                  completion:^(NSArray<NSString *> *result, FlutterError *error) {
+                                    XCTAssertNotNil(error);
+                                    XCTAssertEqualObjects(error.code, @"multiple_request");
+                                    [firstCallExpectation fulfill];
+                                  }];
+  [plugin pickMediaWithMediaSelectionOptions:options
+                                  completion:^(NSArray<NSString *> *result, FlutterError *error){
+                                  }];
+  [self waitForExpectationsWithTimeout:30 handler:nil];
+}
+
+- (void)testPickVideoDuplicateCallCancels API_AVAILABLE(ios(14)) {
+  id mockPhotoLibrary = OCMClassMock([PHPhotoLibrary class]);
+  OCMStub([mockPhotoLibrary authorizationStatusForAccessLevel:PHAccessLevelReadWrite])
+      .andReturn(PHAuthorizationStatusNotDetermined);
+  OCMExpect([mockPhotoLibrary requestAuthorizationForAccessLevel:PHAccessLevelReadWrite
+                                                         handler:OCMOCK_ANY]);
+
+  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];
+
+  FLTSourceSpecification *source = [FLTSourceSpecification makeWithType:FLTSourceTypeCamera
+                                                                 camera:FLTSourceCameraRear];
+  XCTestExpectation *firstCallExpectation = [self expectationWithDescription:@"first call"];
+  [plugin pickVideoWithSource:source
+                  maxDuration:nil
+                   completion:^(NSString *result, FlutterError *error) {
+                     XCTAssertNotNil(error);
+                     XCTAssertEqualObjects(error.code, @"multiple_request");
+                     [firstCallExpectation fulfill];
+                   }];
+  [plugin pickVideoWithSource:source
+                  maxDuration:nil
+                   completion:^(NSString *result, FlutterError *error){
+                   }];
+  [self waitForExpectationsWithTimeout:30 handler:nil];
+}
+
 @end

packages/image_picker/image_picker_ios/ios/Classes/FLTImagePickerPlugin.m

@@ -31,12 +31,6 @@
 
 @interface FLTImagePickerPlugin ()
 
-/**
- * The PHPickerViewController instance used to pick multiple
- * images.
- */
-@property(strong, nonatomic) PHPickerViewController *pickerViewController API_AVAILABLE(ios(14));
-
 /**
  * The UIImagePickerController instances that will be used when a new
  * controller would normally be created. Each call to
@@ -117,15 +111,16 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
     config.filter = [PHPickerFilter imagesFilter];
   }
 
-  _pickerViewController = [[PHPickerViewController alloc] initWithConfiguration:config];
-  _pickerViewController.delegate = self;
-  _pickerViewController.presentationController.delegate = self;
+  PHPickerViewController *pickerViewController =
+      [[PHPickerViewController alloc] initWithConfiguration:config];
+  pickerViewController.delegate = self;
+  pickerViewController.presentationController.delegate = self;
   self.callContext = context;
 
   if (context.requestFullMetadata) {
-    [self checkPhotoAuthorizationForAccessLevel];
+    [self checkPhotoAuthorizationWithPHPicker:pickerViewController];
   } else {
-    [self showPhotoLibraryWithPHPicker:_pickerViewController];
+    [self showPhotoLibraryWithPHPicker:pickerViewController];
   }
 }
 
@@ -201,6 +196,7 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
                      fullMetadata:(NSNumber *)fullMetadata
                        completion:(nonnull void (^)(NSArray<NSString *> *_Nullable,
                                                     FlutterError *_Nullable))completion {
+  [self cancelInProgressCall];
   FLTImagePickerMethodCallContext *context =
       [[FLTImagePickerMethodCallContext alloc] initWithResult:completion];
   context.maxSize = maxSize;
@@ -220,6 +216,7 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
 - (void)pickMediaWithMediaSelectionOptions:(nonnull FLTMediaSelectionOptions *)mediaSelectionOptions
                                 completion:(nonnull void (^)(NSArray<NSString *> *_Nullable,
                                                              FlutterError *_Nullable))completion {
+  [self cancelInProgressCall];
   FLTImagePickerMethodCallContext *context =
       [[FLTImagePickerMethodCallContext alloc] initWithResult:completion];
   context.maxSize = [mediaSelectionOptions maxSize];
@@ -244,6 +241,7 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
                 maxDuration:(nullable NSNumber *)maxDurationSeconds
                  completion:
                      (nonnull void (^)(NSString *_Nullable, FlutterError *_Nullable))completion {
+  [self cancelInProgressCall];
   FLTImagePickerMethodCallContext *context = [[FLTImagePickerMethodCallContext alloc]
       initWithResult:^void(NSArray<NSString *> *paths, FlutterError *error) {
         if (paths.count > 1) {
@@ -393,7 +391,8 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
   }
 }
 
-- (void)checkPhotoAuthorizationForAccessLevel API_AVAILABLE(ios(14)) {
+- (void)checkPhotoAuthorizationWithPHPicker:(PHPickerViewController *)pickerViewController
+    API_AVAILABLE(ios(14)) {
   PHAccessLevel requestedAccessLevel = PHAccessLevelReadWrite;
   PHAuthorizationStatus status =
       [PHPhotoLibrary authorizationStatusForAccessLevel:requestedAccessLevel];
@@ -404,13 +403,9 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
                                      handler:^(PHAuthorizationStatus status) {
                                        dispatch_async(dispatch_get_main_queue(), ^{
                                          if (status == PHAuthorizationStatusAuthorized) {
-                                           [self
-                                               showPhotoLibraryWithPHPicker:self->
-                                                                            _pickerViewController];
+                                           [self showPhotoLibraryWithPHPicker:pickerViewController];
                                          } else if (status == PHAuthorizationStatusLimited) {
-                                           [self
-                                               showPhotoLibraryWithPHPicker:self->
-                                                                            _pickerViewController];
+                                           [self showPhotoLibraryWithPHPicker:pickerViewController];
                                          } else {
                                            [self errorNoPhotoAccess:status];
                                          }
@@ -420,7 +415,7 @@ typedef NS_ENUM(NSInteger, ImagePickerClassType) { UIImagePickerClassType, PHPic
     }
     case PHAuthorizationStatusAuthorized:
     case PHAuthorizationStatusLimited:
-      [self showPhotoLibraryWithPHPicker:_pickerViewController];
+      [self showPhotoLibraryWithPHPicker:pickerViewController];
       break;
     case PHAuthorizationStatusDenied:
     case PHAuthorizationStatusRestricted:

packages/image_picker/image_picker_ios/pubspec.yaml

@@ -2,7 +2,7 @@ name: image_picker_ios
 description: iOS implementation of the image_picker plugin.
 repository: https://github.com/flutter/packages/tree/main/packages/image_picker/image_picker_ios
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+image_picker%22
-version: 0.8.8+2
+version: 0.8.8+3
 
 environment:
   sdk: ">=2.19.0 <4.0.0"