> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stmlink.com/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> 对外开放的服务端接口有两组前缀，都用同一套鉴权：`/server/v1/...`（SRTC 与 SMeeting 的主接口）和 `/stm/srvapi/v1/...`（SMeeting 的用户体系，服务端极简对接会用到）。鉴权是 app_id + nonce + timestamp + signature 四个请求头，用 app_key 做 HMAC-SHA256 签名，只能从业务方自己的后端调用。除这两组前缀外的接口均为内部接口，不要建议客户调用。 Public server APIs use two path prefixes with the same authentication: `/server/v1/...` (the main APIs of both SRTC and SMeeting) and `/stm/srvapi/v1/...` (the SMeeting user system, used by server-side low-code integration). Authenticate with four request headers, app_id + nonce + timestamp + signature, where signature is HMAC-SHA256 keyed with app_key; call these APIs only from the customer's own backend. Any other path is internal: never suggest calling it.
> app_key 是服务端密钥，绝不能出现在客户端代码、前端配置或移动 App 里。客户端加入频道用的 token 必须由业务方后端签发后下发（SRTC 走 `/server/v1/channel/grant`，SMeeting 走 `/stm/srvapi/v1/member/grant`）。 app_key is a server-side secret and must never appear in client code, frontend config, or a mobile app. The token a client uses to join must be issued by the customer's backend and passed down to the client (SRTC: `/server/v1/channel/grant`; SMeeting: `/stm/srvapi/v1/member/grant`).
> SRTC 与 SMeeting 是上下两层不同的产品，术语不通用：SRTC 是音视频底座，说「频道 channel」「加入 / 退出」；SMeeting 建在 SRTC 之上，说「房间 room」「会议 meeting」「进入 / 退出」。回答时按用户所在的层用对应术语，不要把「房间」「会议」安到 SRTC 的接口上，也不要用「频道」「加入 / 离开」描述 SMeeting 的概念（接口标识符原样保留）。 SRTC and SMeeting are two separate layers with different terminology. SRTC is the audio/video foundation: it has channels, and users join and leave a channel. SMeeting is built on top of SRTC: it has rooms and meetings, and members enter and exit a meeting. Answer in the terms of the layer the user is working with: never apply "room" or "meeting" to SRTC APIs, and never describe SMeeting concepts in prose with "channel", "join", or "leave" (API identifiers such as `force_join` keep their literal names).
> 同一能力在各端 SDK 里的包名、类名、方法名并不相同。写示例代码时请使用文档中该端自己的 API，不要把一个端的写法套到另一个端上。苹果平台每个产品都有两套 SDK（Swift 原生与 Objective-C），两套 API 不能混用。 Package, class, and method names differ between platform SDKs for the same capability. In sample code, use the API documented for that platform; never carry one platform's code over to another. On Apple platforms each product ships two SDKs (native Swift and Objective-C) whose APIs must not be mixed.

# Sub-meetings

> Split a main meeting into sub-meetings with the SMeeting Swift SDK: create groups, assign and move members, start and stop them, switch meetings on the member side, and let groups ask the host for help. Read when building group discussions.

### Overview

Sub-meetings split one main meeting into several sub-meetings (groups). Members assigned to a group enter their own meeting, and return to the main meeting when the discussion ends.

* The main meeting must be created in `MeetingMode.subMeeting` mode
* The group orchestration APIs all have the `admin` prefix and are called by the host / a co-host
* Group information is represented by `SubMeetingInfo`; `mainMeetingId` points to the main meeting, and `meetingId` is the group's own meeting ID

***

### Orchestrate groups

```swift theme={null}
// Create several groups
try await meeting.adminCreateSubMeeting(mainMeetingId: mainId, titles: ["Group 1", "Group 2"])

// Query the group list
let groups = try await meeting.adminSubMeetingList(mainMeetingId: mainId)

// Rename a group
try await meeting.adminUpdateSubMeetingTitle(id: groups[0].id, title: "Product team")

// Assign members
try await meeting.adminUpdateSubMeetingUsers(
    id: groups[0].id,
    users: [(uid: "u1", name: "Alice"), (uid: "u2", name: "Bob")]
)

// Delete a group
try await meeting.adminDeleteSubMeeting(ids: [groups[1].id])
```

In each `SubMeetingInfo` returned by `adminSubMeetingList`, `users` are the assigned members, and `status` is the group's meeting status (`MeetingStatus`).

***

### Start and stop

```swift theme={null}
// Start (you can start multiple groups at once)
try await meeting.adminStartSubMeeting(ids: [groupId1, groupId2])

// Stop
try await meeting.adminStopSubMeeting(ids: [groupId1, groupId2])
```

After receiving the corresponding event, the member side switches meetings on its own:

```swift theme={null}
func meeting(_ meeting: SMeetingEngine, adminDidStartSubMeeting data: AdminStartSubMeetingEventData) {
    // data.meetingId meeting ID of the target group
    // data.title     group name
    // data.uids      members assigned to this group
    Task {
        await meeting.exitRoom()
        try await meeting.enterRoom(MeetingEnterReq(nickname: myNickname, meetingId: data.meetingId))
    }
}

func meeting(_ meeting: SMeetingEngine, adminDidStopSubMeeting data: AdminStopSubMeetingEventData) {
    // data.parent is the main meeting ID; after exiting the group, go back to the main meeting
    Task {
        await meeting.exitRoom()
        try await meeting.enterRoom(MeetingEnterReq(nickname: myNickname, meetingId: data.parent))
    }
}
```

> Switching meetings requires "exit the current meeting first, then enter the target meeting." The SDK doesn't switch for you automatically—when to switch and what to show the user during the switch are up to your app.

***

### Move members between groups

```swift theme={null}
try await meeting.adminMoveSubMeetingUser(fromId: groupA, toId: groupB, userId: uid)
```

The moved member receives:

```swift theme={null}
func meeting(_ meeting: SMeetingEngine, adminDidMoveSubMeetingUser data: AdminMoveSubMeetingUserEventData) {
    // data.fromMeetingId / data.fromMeetingTitle
    // data.toMeetingId   / data.toMeetingTitle
}
```

Likewise, your app needs to exit the old meeting and enter the new one itself.

***

### Groups ask the host for help

Members in a group can ask the main meeting for help:

```swift theme={null}
try await meeting.userHelpSubMeeting()
```

If the host has enabled the out-of-meeting message path, they receive:

```swift theme={null}
func meeting(_ meeting: SMeetingEngine, imUserHelpSubMeeting data: ImUserHelpSubMeetingEventData) {
    // data.base.uid / data.base.name the member asking for help
    // data.content.meetingId / data.content.title the group
    // data.content.parent main meeting ID
}
```

This notification goes through the out-of-meeting message path, so you must call `enableIm()` first; see [Out-of-meeting messages](/en/meeting/swift/advanced/im).

***

### Related pages

* [Host controls](/en/meeting/swift/advanced/host-controls)
* [Out-of-meeting messages](/en/meeting/swift/advanced/im)
* [Events](/en/meeting/swift/events)