Objective C API to read and set RtpParameters

webrtc/api/objc/RTCRtpSender.mm

+/*
+ *  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 "RTCRtpSender.h"
+#import "webrtc/api/objc/RTCRtpParameters+Private.h"

[tkchin_webrtc, 2016/04/05 18:48:16]

nit: blank line after first header import

+#import "webrtc/api/objc/RTCRtpSender+Private.h"
+#import "webrtc/api/objc/RTCMediaStreamTrack+Private.h"
+
+#include "webrtc/api/mediastreaminterface.h"
+#include "webrtc/api/rtpsenderinterface.h"
+
+@implementation RTCRtpSender {
+  rtc::scoped_refptr<webrtc::RtpSenderInterface> _nativeRtpSender;
+  RTCMediaStreamTrack* _track;

[tkchin_webrtc, 2016/04/05 18:48:16]

ditto * in file

+}
+
+- (instancetype)initWithNativeRtpSender:
+    (rtc::scoped_refptr<webrtc::RtpSenderInterface>)nativeRtpSender {
+  if (self = [super init]) {
+    _nativeRtpSender = nativeRtpSender;
+    rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> nativeTrack(
+        _nativeRtpSender->track());

[Taylor Brandstetter, 2016/04/05 17:48:03]

I think it would be better if the track wasn't cached, and it was just retrieved
every time "track" is called. That way, the Obj-C RtpSender doesn't need to keep
track of when the track of the native RtpSender changes (due to, for example,
PeerConnection.addTrack).

I know the Java binding caches the track, but that's due to its unique ownership
semantics (the RtpSender is supposed to "dispose" of its track). I plan to
improve how that works at some point.

[skvlad, 2016/04/05 23:21:28]

I've changed the code to create a new track each time.

+    if (nativeTrack) {
+      _track = [[RTCMediaStreamTrack alloc] initWithNativeTrack:nativeTrack];
+    }
+  }
+  return self;
+}
+
+- (RTCRtpParameters*)parameters {
+  return [[RTCRtpParameters alloc]
+      initWithNativeParameters:_nativeRtpSender->GetParameters()];
+}
+
+- (BOOL)setParameters:(RTCRtpParameters*)parameters {
+  return _nativeRtpSender->SetParameters(parameters.nativeParameters);
+}
+
+- (RTCMediaStreamTrack*)track {
+  return _track;
+}
+@end