Add video codec setting to AppRTCMobile on iOS.

webrtc/examples/objc/AppRTCMobile/ARDAppClient.h

 /*
  *  Copyright 2014 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.
  */
 
@@ skipping 42 matching lines @@
 // class should only be called from the main queue.
 @interface ARDAppClient : NSObject
 
 // If |shouldGetStats| is true, stats will be reported in 1s intervals through
 // the delegate.
 @property(nonatomic, assign) BOOL shouldGetStats;
 @property(nonatomic, readonly) ARDAppClientState state;
 @property(nonatomic, weak) id<ARDAppClientDelegate> delegate;
 // Convenience constructor since all expected use cases will need a delegate
 // in order to receive remote tracks.
-- (instancetype)initWithDelegate:(id<ARDAppClientDelegate>)delegate;
+- (instancetype)initWithDelegate:(id<ARDAppClientDelegate>)delegate
+                preferVideoCodec:(NSString*)codec;

[daniela-webrtc, 2017/03/20 13:10:06]

NSString* -> NSString *

[daniela-webrtc, 2017/03/20 13:10:06]

I don't think this is needed as early as the init?
It would be nice to pass all settings the same way i.e either in the initializer
or set as parameters like the media constraints and the bitrate are currently
set.
Having parameters will enable reset of settings when the (ARDApp)client is
cached and not recreated all the time.

 
 // Sets camera constraints.
 - (void)setCameraConstraints:(RTCMediaConstraints *)mediaConstraints;
 
 // Sets maximum bitrate the rtp sender should use.
 - (void)setMaxBitrate:(NSNumber *)maxBitrate;
 
 // Establishes a connection with the AppRTC servers for the given room id.
 // If |isLoopback| is true, the call will connect to itself.
 // If |isAudioOnly| is true, video will be disabled for the call.
 // If |shouldMakeAecDump| is true, an aecdump will be created for the call.
 // If |shouldUseLevelControl| is true, the level controller will be used
 // in the call.
 - (void)connectToRoomWithId:(NSString *)roomId
                  isLoopback:(BOOL)isLoopback
                 isAudioOnly:(BOOL)isAudioOnly
           shouldMakeAecDump:(BOOL)shouldMakeAecDump
       shouldUseLevelControl:(BOOL)shouldUseLevelControl;
 
 // Disconnects from the AppRTC servers and any connected clients.
 - (void)disconnect;
 
 @end