[image_picker] Fix check for iOS 14+ authorization status

[vashworth]

Replace [PHPhotoLibrary authorizationStatus] with [PHPhotoLibrary authorizationStatusForAccessLevel:] for iOS 14+.

According to WWDC 2020 video "Handle the Limited Photos Library in your app", authorizationStatus is deprecated and will not return the newer PHAuthorizationStatusLimited.

Fixes flutter/flutter#113681.

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[vashworth]

So I'm unsure of how to test this change. Since the behavior and UI for PHAuthorizationStatusLimited and PHAuthorizationStatusAuthorized is the same, I can't think of a way to test it with a UITest. And since we're dealing with permissions, I don't think a normal unit test would work either.

Also, I'm waiting to update the changelog/pubspec since I have a different PR for the image_picker that should land soon.

[jmagman]

So I'm unsure of how to test this change. Since the behavior and UI for PHAuthorizationStatusLimited and PHAuthorizationStatusAuthorized is the same, I can't think of a way to test it with a UITest. And since we're dealing with permissions, I don't think a normal unit test would work either.

Ugh, sorry, the checkPhotoAuthorizationForAccessLevel path is totally untested, and the test file is kind of a mess. This would work:

- (void)testPickImageRequestAuthorization 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];

  [plugin pickImageWithSource:[FLTSourceSpecification makeWithType:FLTSourceTypeGallery
                                                            camera:FLTSourceCameraFront]
                      maxSize:[[FLTMaxSize alloc] init]
                      quality:nil
                 fullMetadata:@YES
                   completion:^(NSString *result, FlutterError *error){
                   }];
  OCMVerifyAll(mockPhotoLibrary);
}

- (void)testPickImageAuthorizationDenied API_AVAILABLE(ios(14)) {
  id mockPhotoLibrary = OCMClassMock([PHPhotoLibrary class]);
  OCMStub([mockPhotoLibrary authorizationStatusForAccessLevel:PHAccessLevelReadWrite])
      .andReturn(PHAuthorizationStatusDenied);

  FLTImagePickerPlugin *plugin = [[FLTImagePickerPlugin alloc] init];

  XCTestExpectation *resultExpectation = [self expectationWithDescription:@"result"];

  [plugin pickImageWithSource:[FLTSourceSpecification makeWithType:FLTSourceTypeGallery
                                                            camera:FLTSourceCameraFront]
                      maxSize:[[FLTMaxSize alloc] init]
                      quality:nil
                 fullMetadata:@YES
                   completion:^(NSString *result, FlutterError *error) {
                     XCTAssertNil(result);
                     XCTAssertEqualObjects(error.code, @"photo_access_denied");
                     XCTAssertEqualObjects(error.message, @"The user did not allow photo access.");
                     [resultExpectation fulfill];
                   }];
  [self waitForExpectationsWithTimeout:30 handler:nil];
}

The first one would fail via OCMExpect/OCMVerifyAll if -requestAuthorizationForAccessLevel:PHAccessLevelReadWrite wasn't called. The second would fail if the completion didn't fail with the photo_access_denied error.

[jmagman]

LGTM!

[jmagman]

Up to you, but it might be clearer to get rid of the local variable and pass in PHAccessLevelReadWrite in two places. Accessing an enum is so cheap there's no reason to cache it.

Suggested change

	PHAccessLevel requestedAccessLevel = PHAccessLevelReadWrite;
	PHAuthorizationStatus status =
	[PHPhotoLibrary authorizationStatusForAccessLevel:requestedAccessLevel];
	PHAuthorizationStatus status =
	[PHPhotoLibrary authorizationStatusForAccessLevel:PHAccessLevelReadWrite];

[cyanglaz]

LGTM!