如何在iOS上使用RTCMediaConstraints

Question

创建新优惠：

[_peerConnection createOfferWithDelegate:self
                               constraints:[self defaultOfferConstraints]];

- (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;
}

当我将true更改为false时，它似乎与RTCSessionDescription无关。我打印出来了

- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didCreateSessionDescription:(RTCSessionDescription *)sdp
                          error:(NSError *)error

问题：

• 约束是否与RTCSessionDescription有关？
• 哪些密钥支持RTCPair？