Use new RTCCameraVideoCapturer in AppRTCMobile.

webrtc/examples/objc/AppRTCMobile/ARDCaptureController.m

+/*
+ *  Copyright 2017 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 "ARDCaptureController.h"
+
+#import "ARDSettingsModel.h"
+
+@implementation ARDCaptureController {
+  RTCCameraVideoCapturer *_capturer;
+  ARDSettingsModel *_settings;
+  BOOL _usingFrontCamera;
+}
+
+- (instancetype)initWithCapturer:(RTCCameraVideoCapturer *)capturer
+                        settings:(ARDSettingsModel *)settings {
+  if ([super init]) {
+    _capturer = capturer;
+    _settings = settings;
+    _usingFrontCamera = YES;
+  }
+
+  return self;
+}
+
+- (void)startCapture {
+  AVCaptureDevicePosition position =
+      _usingFrontCamera ? AVCaptureDevicePositionFront : AVCaptureDevicePositionBack;
+  AVCaptureDevice *device = [self findDeviceForPosition:position];
+  AVCaptureDeviceFormat *format = [self selectFormatForDevice:device];
+  int fps = [self selectFpsForFormat:format];
+
+  [_capturer startCaptureWithDevice:device format:format fps:fps];
+}
+
+- (void)stopCapture {
+  [_capturer stopCapture];
+}
+
+- (void)switchCamera {
+  _usingFrontCamera = !_usingFrontCamera;
+  [self startCapture];
+}
+
+#pragma mark - Private
+
+- (AVCaptureDevice *)findDeviceForPosition:(AVCaptureDevicePosition)position {
+  NSArray<AVCaptureDevice *> *captureDevices = [RTCCameraVideoCapturer captureDevices];
+  for (AVCaptureDevice *device in captureDevices) {
+    if (device.position == position) {
+      return device;
+    }
+  }
+  return captureDevices[0];
+}
+
+- (AVCaptureDeviceFormat *)selectFormatForDevice:(AVCaptureDevice *)device {
+  NSArray<AVCaptureDeviceFormat *> *formats =
+      [RTCCameraVideoCapturer supportedFormatsForDevice:device];
+  int targetWidth = [_settings currentVideoResolutionWidthFromStore];
+  int targetHeight = [_settings currentVideoResolutionHeightFromStore];
+  AVCaptureDeviceFormat *selectedFormat = nil;
+  int currentDiff = INT_MAX;
+
+  for (AVCaptureDeviceFormat *format in formats) {
+    CMVideoDimensions dimension = CMVideoFormatDescriptionGetDimensions(format.formatDescription);
+    int diff = abs(targetWidth - dimension.width) + abs(targetHeight - dimension.height);
+    if (diff < currentDiff) {
+      selectedFormat = format;
+      currentDiff = diff;
+    }
+  }
+
+  NSAssert(selectedFormat != nil, @"No suitable capture format found.");
+  return selectedFormat;
+}
+
+- (int)selectFpsForFormat:(AVCaptureDeviceFormat *)format {
+  Float64 maxFramerate = 0;
+  for (AVFrameRateRange *fpsRange in format.videoSupportedFrameRateRanges) {
+    maxFramerate = fmax(maxFramerate, fpsRange.maxFrameRate);
+  }
+  return maxFramerate;
+}
+
+@end