Agora RTC Objective-C API Reference Refactor

### - r -

- receivedBitrate : AgoraRtcRemoteAudioStats , AgoraRtcRemoteVideoStats
- receivedFrameRate : AgoraRtcRemoteVideoStats
- receivedSampleRate : AgoraRtcRemoteAudioStats
- recorderFileName : AgoraMediaRecorderInfo
- recorderInfoUpdateInterval : AgoraMediaRecorderConfiguration
- recordingChannel : AgoraAudioRecordingConfiguration
- rect : AgoraTranscodingVideoStream
- rednessLevel : AgoraBeautyOptions
- releaseTime : AgoraMusic
- remoteJoined2PacketReceived : AgoraVideoRenderingTracingInfo
- remoteJoined2SetView : AgoraVideoRenderingTracingInfo
- remoteJoined2UnmuteVideo : AgoraVideoRenderingTracingInfo
- remoteUid : AgoraExtensionInfo
- remoteUserUid : AgoraTranscodingVideoStream
- remoteVisible : AgoraMetachatAvatarModelInfo
- rendererOutputFrameRate : AgoraRtcRemoteVideoStats
- renderMode : AgoraRtcVideoCanvas
- renderTimeMs : AgoraAudioFrame , AgoraExtVideoFrame , AgoraOutputVideoFrame , AgoraVideoFilterFrame
- resolution : AgoraMvProperty
- right : AgoraMetachatPositionInfo , AgoraSpatialAudioZone
- rightLength : AgoraSpatialAudioZone
- roomName : AgoraMetachatEnterSceneConfig
- rotation : AgoraEncodedVideoFrameInfo , AgoraExtVideoFrame , AgoraOutputVideoFrame , AgoraRtcMediaStreamInfo , AgoraRtcVideoCanvas , AgoraVideoFilterFrame , AgoraVideoFrame
- rtcEngine : AgoraCloudSpatialAudioConfig , AgoraLocalSpatialAudioConfig , AgoraMetachatConfig , AgoraMusicContentCenterConfig
- rtmToken : AgoraMetachatConfig
- rtpTimestamp : AgoraAudioFrame
- rtt : AgoraLastmileProbeResult
- rxAudioBytes : AgoraChannelStats , AgoraRtcRemoteAudioStats
- rxAudioKBitrate : AgoraChannelStats
- rxBytes : AgoraChannelStats
- rxKBitrate : AgoraChannelStats
- rxPacketLossRate : AgoraChannelStats
- rxStreamType : AgoraRtcRemoteVideoStats
- rxVideoBytes : AgoraChannelStats , AgoraRtcRemoteVideoStats
- rxVideoKBitrate : AgoraChannelStats