Fixed that RTCCameraPreviewView did not rotate the video on device rotation.

webrtc/sdk/objc/Framework/Classes/RTCCameraPreviewView.m

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #import "WebRTC/RTCCameraPreviewView.h"
 
 #import <AVFoundation/AVFoundation.h>
+#import <UIKit/UIKit.h>
 
 #import "RTCDispatcher+Private.h"
 
 @implementation RTCCameraPreviewView
 
 @synthesize captureSession = _captureSession;
 
 + (Class)layerClass {
   return [AVCaptureVideoPreviewLayer class];
 }
 
 - (void)setCaptureSession:(AVCaptureSession *)captureSession {
   if (_captureSession == captureSession) {
     return;
   }
   _captureSession = captureSession;
   AVCaptureVideoPreviewLayer *previewLayer = [self previewLayer];
   [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                                block:^{
     previewLayer.session = captureSession;
   }];
 }
 
+- (void)layoutSubviews {
+  [super layoutSubviews];
+
+  // Update the video orientation based on the device orientation.
+  [self setCorrectVideoOrientation];
+}
+
+- (void)setCorrectVideoOrientation {
+  // Get current device orientation.
+  UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
+  AVCaptureVideoPreviewLayer *previewLayer = [self previewLayer];
+
+  // First check if we are allowed to set the video orientation.
+  if (previewLayer.connection.isVideoOrientationSupported) {
+    // Set the video orientation based on device orientation.
+    if (deviceOrientation == UIInterfaceOrientationPortraitUpsideDown) {
+      previewLayer.connection.videoOrientation =
+          AVCaptureVideoOrientationPortraitUpsideDown;
+    } else if (deviceOrientation == UIInterfaceOrientationLandscapeRight) {
+      previewLayer.connection.videoOrientation =
+          AVCaptureVideoOrientationLandscapeRight;
+    } else if (deviceOrientation == UIInterfaceOrientationLandscapeLeft) {
+      previewLayer.connection.videoOrientation =
+          AVCaptureVideoOrientationLandscapeLeft;
+    } else {
+      previewLayer.connection.videoOrientation =
+          AVCaptureVideoOrientationPortrait;
+    }
+  }
+}
+
 #pragma mark - Private
 
 - (AVCaptureVideoPreviewLayer *)previewLayer {
   return (AVCaptureVideoPreviewLayer *)self.layer;
 }
 
 @end