Added the API to create an RTCRtpSender to the Objective C wrapper.

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCRtpSender.h

 /*
  *  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 <Foundation/Foundation.h>
 
 #import <WebRTC/RTCMacros.h>
 #import <WebRTC/RTCMediaStreamTrack.h>
 #import <WebRTC/RTCRtpParameters.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
 RTC_EXPORT
 @protocol RTCRtpSender <NSObject>
 
+/** A unique identifier for this sender. */
+@property(nonatomic, readonly) NSString *senderId;
+
 /** The currently active RTCRtpParameters, as defined in
  *  https://www.w3.org/TR/webrtc/#idl-def-RTCRtpParameters.
  */
-@property(nonatomic, readonly) RTCRtpParameters *parameters;
+@property(nonatomic, copy) RTCRtpParameters *parameters;
 
 /** The RTCMediaStreamTrack associated with the sender.
  *  Note: reading this property returns a new instance of
  *  RTCMediaStreamTrack. Use isEqual: instead of == to compare
  *  RTCMediaStreamTrack instances.
  */
-@property(nonatomic, readonly) RTCMediaStreamTrack *track;
-
-/** Set the new RTCRtpParameters to be used by the sender.
- *  Returns YES if the new parameters were applied, NO otherwise.
- */
-- (BOOL)setParameters:(RTCRtpParameters *)parameters;
+@property(nonatomic, copy, nullable) RTCMediaStreamTrack *track;
 
 @end
 
 RTC_EXPORT
 @interface RTCRtpSender : NSObject <RTCRtpSender>
 
 - (instancetype)init NS_UNAVAILABLE;
 
 @end
 
 NS_ASSUME_NONNULL_END