Add video codec setting to AppRTCMobile on iOS.

webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsModel.m

 /*
  *  Copyright 2016 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 "ARDSettingsModel+Private.h"
 #import "ARDSettingsStore.h"
 #import "WebRTC/RTCMediaConstraints.h"
 
 NS_ASSUME_NONNULL_BEGIN
 static NSArray<NSString *> *videoResolutionsStaticValues() {
   return @[ @"640x480", @"960x540", @"1280x720" ];
 }
 
+static NSArray<NSString *> *videoCodecsStaticValues() {
+  return @[ @"H264", @"VP8", @"VP9" ];
+}
+
 @interface ARDSettingsModel () {
   ARDSettingsStore *_settingsStore;
 }
 @end
 
 @implementation ARDSettingsModel
 
 - (NSArray<NSString *> *)availableVideoResoultionsMediaConstraints {
   return videoResolutionsStaticValues();
 }
 
 - (NSString *)currentVideoResoultionConstraintFromStore {
   NSString *constraint = [[self settingsStore] videoResolutionConstraints];
   if (!constraint) {
     constraint = [self defaultVideoResolutionMediaConstraint];
     // To ensure consistency add the default to the store.
     [[self settingsStore] setVideoResolutionConstraints:constraint];
   }
   return constraint;
 }
 
 - (BOOL)storeVideoResoultionConstraint:(NSString *)constraint {
   if (![[self availableVideoResoultionsMediaConstraints] containsObject:constraint]) {
     return NO;
   }
   [[self settingsStore] setVideoResolutionConstraints:constraint];
   return YES;
 }
 
+- (NSArray<NSString *> *)availableVideoCodecs {
+  return videoCodecsStaticValues();
+}
+
+- (NSString *)currentVideoCodecSettingFromStore {
+  NSString *videoCodec = [[self settingsStore] videoCodec];
+  if (!videoCodec) {
+    videoCodec = [self defaultVideoCodecSetting];
+    [[self settingsStore] setVideoCodec:videoCodec];
+  }
+  return videoCodec;
+}
+
+- (BOOL)storeVideoCodecSetting:(NSString *)videoCodec {
+  if (![[self availableVideoCodecs] containsObject:videoCodec]) {
+    return NO;
+  }
+  [[self settingsStore] setVideoCodec:videoCodec];
+  return YES;
+}
+
 - (nullable NSNumber *)currentMaxBitrateSettingFromStore {
   return [[self settingsStore] maxBitrate];
 }
 
 - (void)storeMaxBitrateSetting:(nullable NSNumber *)bitrate {
   [[self settingsStore] setMaxBitrate:bitrate];
 }
 
 #pragma mark - Testable
 
@@ skipping 26 matching lines @@
   if (index != 0 && index != 1) {
     return nil;
   }
   NSArray *components = [constraint componentsSeparatedByString:@"x"];
   if (components.count != 2) {
     return nil;
   }
   return components[index];
 }
 
+- (NSString *)defaultVideoCodecSetting {
+  return videoCodecsStaticValues()[0];
+}
+
 #pragma mark - Conversion to RTCMediaConstraints
 
 - (nullable NSDictionary *)currentMediaConstraintFromStoreAsRTCDictionary {
   NSDictionary *mediaConstraintsDictionary = nil;
 
   NSString *widthConstraint = [self currentVideoResolutionWidthFromStore];
   NSString *heightConstraint = [self currentVideoResolutionHeightFromStore];
   if (widthConstraint && heightConstraint) {
     mediaConstraintsDictionary = @{
       kRTCMediaConstraintsMinWidth : widthConstraint,
       kRTCMediaConstraintsMinHeight : heightConstraint
     };
   }
   return mediaConstraintsDictionary;
 }
 
 @end
 NS_ASSUME_NONNULL_END