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"
+#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;
+}
+
+- (instancetype)initWithNativeRtpSender:
+    (rtc::scoped_refptr<webrtc::RtpSenderInterface>)nativeRtpSender {
+  if (self = [super init]) {
+    _nativeRtpSender = nativeRtpSender;
+  }
+  return self;
+}
+
+- (RTCRtpParameters *)parameters {
+  return [[RTCRtpParameters alloc]
+      initWithNativeParameters:_nativeRtpSender->GetParameters()];
+}
+
+- (BOOL)setParameters:(RTCRtpParameters *)parameters {
+  return _nativeRtpSender->SetParameters(parameters.nativeParameters);
+}
+
+- (RTCMediaStreamTrack *)track {
+  rtc::scoped_refptr<webrtc::MediaStreamTrackInterface> nativeTrack(
+    _nativeRtpSender->track());
+  if (nativeTrack) {
+    return [[RTCMediaStreamTrack alloc] initWithNativeTrack:nativeTrack];

[tkchin_webrtc, 2016/04/06 22:04:49]

is this safe? If someone decides to store RTCMediaStreamTrack in ObjC land
somewhere after getting it here, is it possible for the track to change
underneath? In that case, would it be better to cache a copy here and just
change the native track on the cached RTCMediaStreamTrack instead?

[skvlad, 2016/04/08 19:33:19]

As discussed offline, returning a new track each time is conditionally safe if
the application compares them with isEqual: and not ==. However, we need to
decide a general approach for managing object identity in both Java and ObjC
wrappers. I have opened a bug for that:
https://bugs.chromium.org/p/webrtc/issues/detail?id=5756

+  }
+  return nil;
+}

[tkchin_webrtc, 2016/04/06 22:04:49]

nit: blank line after }

[skvlad, 2016/04/08 19:33:19]

Done.

+@end