Implementing Audio and Video Calls

This tutorial helps developers quickly understand and integrate the core functionalities of CallKit SDK (RC's audio and video calling capability library). CallKit is an audio/video calling SDK built upon CallLib, featuring default call interfaces for one-to-one and multi-party scenarios. You can rapidly implement calling features by integrating it. We also provide open-source code for this module (GitHub · Gitee), allowing customization based on your business needs.

Participant Limit

• Considering mobile device bandwidth (especially with multi-stream video) and UI interaction, we recommend limiting video calls to 16 participants and audio-only calls to 32 participants per session. Exceeding these limits may degrade call quality.
• CallKit enforces default limits: up to 7 participants for video calls and 20 for audio calls. Adjustments can be made in the open-source code (modify RCCall's maxMultiVideoCallUserNumber and maxMultiAudioCallUserNumber), but we advise staying within recommended thresholds.

Environment Requirements

• Xcode 11 or later.
• iOS 9.0 or later for Apple devices.
• Physical devices are required for testing audio/video features.
• CocoaPods 1.10.0 or later if using CocoaPods integration (CallKit SDK 5.1.1+ uses XCFramework, fully supported from CocoaPods 1.10.0).

tip

For CocoaPods setup, refer to Installing CocoaPods.

Prerequisites

1. Register a developer account on the RC Console. Upon registration, a development environment app is automatically created.

2. Obtain your App Key from the console's Basic Info page. This page also displays your App Secret and data center location.
   

   tip

   Each app has two distinct App Keys for development and production environments, with isolated data. Before launch, switch to the production App Key for full testing.

Service Activation

Audio/video services are disabled by default for new RC apps. You must enable them via the console before using any RC audio/video features.

tip

• Configuration changes (activation/deactivation) take effect within 15 minutes.
• Client-side updates may take up to 2 hours. Reinstalling the app forces immediate configuration refresh.

SDK Integration

RC supports two integration methods: CocoaPods remote dependency or local XCFramework import. Below demonstrates CocoaPods.

1. If your project lacks a Podfile, run pod init in the project root to generate one. Add this line to the Podfile:

   pod 'RongCloudRTC/RongCallKit', '~> x.y.z'
   tip

   • CallKit auto-downloads compatible IMKit versions (no manual specification needed). Note: From 5.2.0 to 5.4.4 (exclusive), CallKit and IMKit/IMLib must share identical version numbers (first three digits). Post-5.4.4, only the first two digits must match. CallKit 5.4.4 cannot pair with IMKit/IMLib versions below 5.4.4.
   • Replace x.y.z with the latest CallKit version from RC SDK Downloads or via pod search RongCloudRTC after running pod repo update.

2. In the terminal, navigate to the Podfile directory and execute:

   pod install
   tip

   If encountering version conflicts (e.g., CocoaPods could not find compatible versions), run pod repo update before pod install.

3. Open the generated .xcworkspace file in Xcode.

SDK Initialization

CallKit relies on IM SDK for signaling. Initialize IM SDK using init with your App Key and RCInitOption (initialization config).

Import the IM SDK header first:

#import <RongIMKit/RongIMKit.h>

RCInitOption encapsulates areaCode (data center region), naviServer, fileServer, statisticServer, and crashMonitorEnable. See Initialization.

For Beijing Data Center (default), omit RCInitOption:

NSString *appKey = @"Your_AppKey"; // example: bos9p5rlcm2ba
RCInitOption *initOption = nil;

[[RCIM sharedRCIM] initWithAppKey:appKey option:initOption];

For global data centers, specify the areaCode:

NSString *appKey = @"Your_AppKey"; // example: bos9p5rlcm2ba
RCInitOption *initOption = [[RCInitOption alloc] init];
initOption.areaCode = RCAreaCodeSG; // Singapore Data Center

[[RCIM sharedRCIM] initWithAppKey:appKey option:initOption];

tip

• For CallKit versions <5.4.2 (dev) or ≤5.3.8 (stable), use initWithAppKey directly. See Initialization.
• Ensure IM SDK initialization and connection precede CallKit delegate setup.

Connecting to IM Server

A user Token is an authentication credential tied to a user ID, serving as their unique identifier in RC. Audio/video signaling depends on IM services, requiring a valid Token for connection.

In production, obtain Tokens via your app server using IM Server API User Registration.

[[RCIM sharedRCIM] connectWithToken:@"Token_from_your_server"
                           dbOpened:^(RCDBErrorCode code) {
                               if (code != RCDBErrorCode_Success) {
                                   // Handle database open failure
                               }
                           }
                            success:^(NSString *userId) {
                               // Handle connection success
                           }
                              error:^(RCConnectErrorCode status) {
                               // Handle connection failure
                           }];

Caller Implementation

Apps typically handle both calling and receiving logic simultaneously.

Initiating One-to-One Calls

Method Signature

- (void)startSingleCall:(NSString *)targetId mediaType:(RCCallMediaType)mediaType;

Parameters

Parameter	Type	Required	Description
targetId	NSString	Yes	Recipient's user ID
mediaType	RCCallMediaType	Yes	Media type (audio/video)

Example:

[[RCCall sharedRCCall] startSingleCall:@"recipientUserId" mediaType:RCCallMediaVideo];

Initiating Multi-Party Calls

Multi-party calls require a ConversationType_GROUP, where all participants share the same group ID.

Method Signature

- (void)startMultiCallViewController:(RCConversationType)conversationType
                            targetId:(NSString *)targetId
                           mediaType:(RCCallMediaType)mediaType
                          userIdList:(NSArray *)userIdList;

Parameters:

Parameter	Type	Required	Description
conversationType	RCConversationType	Yes	Conversation type
targetId	NSString	Yes	Group ID
mediaType	RCCallMediaType	Yes	Media type
userIdList	NSArray	Yes	Recipient user IDs

Example:

[[RCCall sharedRCCall] startMultiCallViewController:ConversationType_GROUP
                                           targetId:@"groupId"
                                          mediaType:RCCallMediaVideo
                                         userIdList:@[@"userA", @"userB", @"userC"]];

Member Selection for Calls

This method first displays a member selection UI, then initiates a multi-party call. For group calls, implement groupMemberDataSource.

Method Signature

- (void)startMultiCall:(RCConversationType)conversationType
              targetId:(NSString *)targetId
             mediaType:(RCCallMediaType)mediaType;

Parameters:

Parameter	Type	Required	Description
conversationType	RCConversationType	Yes	Conversation type
targetId	NSString	Yes	Group ID
mediaType	RCCallMediaType	Yes	Media type

Example:

[[RCCall sharedRCCall] startMultiCall:ConversationType_GROUP
                             targetId:@"groupId"
                            mediaType:RCCallMediaVideo];

Callee Implementation

CallKit implements RCCallReceiveDelegate (incoming call handling) and RCCallSessionDelegate (call state) from RongCallLib by default. Recipients see an auto-displayed call UI—click Answer to join.

When the app is backgrounded or closed, incoming calls trigger notifications. Tapping the notification launches the app and displays the call UI after IM connection.

User Profile Display

Call UI user profiles rely on IM user info setup. See User Profile Configuration.

Customization

• Plugins: CallKit supports official or FaceUnity beauty filters (requires CallKit ≥5.4.0). See CallLib docs Beauty Filters.