Fixed focus mode in AVFLiveVideo

Summary: The focus mode needs to be `AVCaptureFocusModeLocked` in case the user specifies a custom focus (`AVCaptureFocusModeContinuousAutoFocus` re-set the focus back to an auto focus immediately).

Reviewed By: enpe

Differential Revision: D67607868

fbshipit-source-id: 4ab3e7b9a61ec29eeb415b1f3b26d7da2b03775f

impl/ocean/media/avfoundation/AVFLiveVideo.mm

@@ -385,11 +385,13 @@ - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CM
 				if ([captureDevice_ isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus])
 				{
 					[captureDevice_ setFocusMode:AVCaptureFocusModeContinuousAutoFocus];
+
 					result = true;
 				}
 				else if ([captureDevice_ isFocusModeSupported:AVCaptureFocusModeAutoFocus])
 				{
 					[captureDevice_ setFocusMode:AVCaptureFocusModeAutoFocus];
+
 					result = true;
 				}
 				else
@@ -401,8 +403,9 @@ - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CM
 			{
 				if (captureDevice_.isLockingFocusWithCustomLensPositionSupported)
 				{
+					[captureDevice_ setFocusMode:AVCaptureFocusModeLocked];
 					[captureDevice_ setFocusModeLockedWithLensPosition:position completionHandler:nil];
-					[captureDevice_ setFocusMode:AVCaptureFocusModeContinuousAutoFocus];
+
 					result = true;
 				}
 			}