Swift print（）打印类型名称，而不是枚举关联值

Question

我正在用WebRTC的委托方法打印几个枚举。比较它们或使用switch语句都可以正常工作，但是其中一个枚举只是打印其类型名称而不是关联的值：

func peerConnection(_ peerConnection: RTCPeerConnection, didChange newState: RTCPeerConnectionState) {
    // I don't know why this only prints the type name and not the associated value
    print ("peerConnectionState \(newState)")
}

func peerConnection(_ peerConnection: RTCPeerConnection, didChange newState: RTCIceConnectionState) {
    print("ICEConnectionState: \(newState)")
}

此打印

peerConnectionState: RTCPeerConnectionState
ICEConnectionState: connected

RTCPeerConnectionState永远不会打印其关联值，即使我检查了它的rawValue，它也是枚举的有效成员。两者都在PeerConnectionState.h中定义，如下所示：

/** Represents the ice connection state of the peer connection. */
typedef NS_ENUM(NSInteger, RTCIceConnectionState) {
  RTCIceConnectionStateNew,
  RTCIceConnectionStateChecking,
  RTCIceConnectionStateConnected,
  RTCIceConnectionStateCompleted,
  RTCIceConnectionStateFailed,
  RTCIceConnectionStateDisconnected,
  RTCIceConnectionStateClosed,
  RTCIceConnectionStateCount,
};

/** Represents the combined ice+dtls connection state of the peer connection. */
typedef NS_ENUM(NSInteger, RTCPeerConnectionState) {
  RTCPeerConnectionStateNew,
  RTCPeerConnectionStateConnecting,
  RTCPeerConnectionStateConnected,
  RTCPeerConnectionStateDisconnected,
  RTCPeerConnectionStateFailed,
  RTCPeerConnectionStateClosed,
};

我对ObjC-Swift桥接不了解很多，这一切似乎都“奏效”。似乎只影响print（）的两个枚举有什么区别？