本地RTCMediaStream不起作用

Question

一旦发出“call”，我就会使用下面的代码创建本地视频流。我的iPhone 6的本地媒体流未生成，但远程媒体流在我的手机上运行正常。有谁知道为什么我无法获得iPhone的本地媒体流？

我正在使用带有node.js的Kurento Media Server。

- (RTCMediaStream *)createLocalMediaStream {

    RTCMediaConstraints *constraints = [self defaultPeerConnectionConstraints];
    self.peerConnection = [self.peerConnectionFactory peerConnectionWithICEServers:server
                                                 constraints:constraints
                                                    delegate:self];
    RTCMediaStream *localStream = [self createLocalMediaStream];
    [self.peerConnection addStream:localStream];
    [_peerConnection createOfferWithDelegate:self constraints:[self defaultOfferConstraints]];

    RTCMediaStream* localStream = [self.peerConnectionFactory mediaStreamWithLabel:@"ARDAMS"];
    RTCVideoTrack* localVideoTrack = nil;

#if !TARGET_IPHONE_SIMULATOR && TARGET_OS_IPHONE
    NSString *cameraID = nil;
    for (AVCaptureDevice *captureDevice in
         [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]) {
        if (captureDevice.position == AVCaptureDevicePositionFront) {
            cameraID = [captureDevice localizedName];
            break;
        }
    }
    NSAssert(cameraID, @"Unable to get the front camera id");

    RTCVideoCapturer *capturer = [RTCVideoCapturer capturerWithDeviceName:cameraID];
    RTCMediaConstraints* constraints = [self defaultMediaStreamConstraints];
    RTCVideoSource *videoSource = [self.peerConnectionFactory videoSourceWithCapturer:capturer constraints:constraints];

    localVideoTrack =
    [self.peerConnectionFactory videoTrackWithID:@"ARDAMSv0" source:videoSource];
    if (localVideoTrack) {
        [localStream addVideoTrack:localVideoTrack];
    }
    [self.delegate connectionManager:self didReceiveLocalVideoTrack:localVideoTrack];
#endif
    [localStream addAudioTrack:[self.peerConnectionFactory audioTrackWithID:@"ARDAMSa0"]];
    return localStream;
}

- (RTCMediaConstraints *)defaultPeerConnectionConstraints {
    NSArray *optionalConstraints = @[
                                     [[RTCPair alloc] initWithKey:@"DtlsSrtpKeyAgreement" value:@"true"]
                                     ];
    RTCMediaConstraints* constraints =
    [[RTCMediaConstraints alloc] initWithMandatoryConstraints:nil optionalConstraints:optionalConstraints];
    return constraints;
}

- (RTCMediaConstraints *)defaultOfferConstraints {
    NSArray *mandatoryConstraints = @[
                                      [[RTCPair alloc] initWithKey:@"OfferToReceiveAudio" value:@"true"],
                                      [[RTCPair alloc] initWithKey:@"OfferToReceiveVideo" value:@"true"]
                                      ];
    RTCMediaConstraints* constraints = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:mandatoryConstraints optionalConstraints:nil];
    return constraints;
}

- (RTCMediaConstraints *)defaultMediaStreamConstraints {    
    NSArray *mandatoryConstraints = @[
                                      [[RTCPair alloc] initWithKey:@"maxWidth" value:@"640"],
                                      [[RTCPair alloc] initWithKey:@"minWidth" value:@"640"],
                                      [[RTCPair alloc] initWithKey:@"maxHeight" value:@"480"],
                                      [[RTCPair alloc] initWithKey:@"minHeight" value:@"480"],
                                      [[RTCPair alloc] initWithKey:@"maxFrameRate" value:@"30"],
                                      [[RTCPair alloc] initWithKey:@"minFrameRate" value:@"5"],
                                      [[RTCPair alloc] initWithKey:@"googLeakyBucket" value:@"true"]
                                      ];

    RTCMediaConstraints *constrains = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:mandatoryConstraints optionalConstraints:nil];
    return constrains;
}