Step 3: Login and Logout
Overview
After initializing the Chat SDK, you need to call the SDK login API to authenticate your account to get the permissions to use message, conversation, and other features.
Caution:
Only the conversation acquisition API can be called immediately after you call the login API, and other APIs can be called only after you have successfully logged in to the SDK. Therefore, make sure that you have logged in successfully before using other features; otherwise, such features may become abnormal or unavailable.
Login
You don't need to sign up on your first login, as you will automatically sign up if the login is successful.
You can call the
login API (details) to log in.Key parameters of the
login API are as follows:Parameter | Description | Remarks |
UserID | Unique user ID | It can contain up to 32 bytes of letters (a-z and A-Z), digits (0-9), underscores (_), and hyphens (-). |
UserSig | Login ticket. | It is calculated by your business server to ensure security. For more information on the calculation method, see Generating UserSig. |
You can call the
login API in the following scenarios:When you use features of the Chat SDK for the first time after the app is started.
The ticket expires before login: The callback of the
login API returns the error ERR_USER_SIG_EXPIRED (6206) or ERR_SVR_ACCOUNT_USERSIG_EXPIRED (70001), and you need to generate a new userSig and log in again.The ticket expires when you are online: You may receive the
onUserSigExpired callback (details) when you are online. In this case, you need to generate a new userSig to log in again.A user is kicked offline: When a user is kicked offline, the Chat SDK will notify you through the
onKickedOffline callback (details). In this case, you can prompt the user and call login to log in again.You don't need to call the
login API in the following scenarios:When your network is disconnected and then reconnected. In this case, the SDK automatically goes online.
When a login process is already running. In this case, repeated login is unnecessary.
Note:
1. After you call the Chat SDK API and log in successfully, DAU calculation will start; therefore, call the login API as needed to avoid a high DAU.
2. You cannot log in to multiple Chat SDK accounts of the same application at the same time; otherwise, only the last logged in account will be online.
Sample code:
String userID = "your user id";String userSig = "userSig from your server";V2TimCallback res = await TencentImSDKPlugin.v2TIMManager.login(userID: userID, userSig: userSig);if(res.code == 0){// Logic for successful login}else{// Logic for failed login}
Getting the login user
After logging in successfully, call the
getLoginUser API (details) to get the UserID.
If the login fails, the UserID will be empty.Sample code:
// After successful login,// call `getLoginUser` to get the `UserID`.V2TimValueCallback<String> getLoginUserRes =await TencentImSDKPlugin.v2TIMManager.getLoginUser();if (getLoginUserRes.code == 0) {// Obtained successfullygetLoginUserRes.data; // `getLoginUserRes.data` gets the `UserID` of the login user}
Getting the login status
Call the
getLoginStatus API (details) to get the login status. If a user is logged in or logging in, don't call the login API frequently. The Chat SDK supports the following login status:Login Status | Description |
V2TIM_STATUS_LOGINED (1) | Logged in |
V2TIM_STATUS_LOGINING (2) | Logging in |
V2TIM_STATUS_LOGOUT (3) | Not logged in |
Sample code:
// After successful login,// call `getLoginStatus` to get the status of the login user.V2TimValueCallback<int> getLoginStatusRes =await TencentImSDKPlugin.v2TIMManager.getLoginStatus();if (getLoginStatusRes.code == 0) {int? status = getLoginStatusRes.data; // `getLoginStatusRes.data` gets the user's login status value.if (status == 1) {// Logged in} else if (status == 2) {// Logging in} else if (status == 3) {// Not logged in}}
Multi-Client Login and Kickout
You can configure multi-client login policies for the Chat SDK in the Tencent Cloud console.
There are multiple multi-client login policies, such as A user can be concurrently online on a mobile or desktop platform and the web platform or A user can be concurrently online on all platforms.
For related configuration, see Login settings.
You can configure the Max Login Instances per User per Platform for the Chat SDK in the Tencent Cloud console, that is, the maximum number of instances on the same platform that can be concurrently online.
This feature is available only for the Ultimate edition. A user can be concurrently online on up to ten clients on the web platform or on up to three clients on the Android, iPhone, iPad, Windows, or macOS platform (the maximum number of clients that can be concurrently online on Flutter is subject to the actual compilation result).
For related configuration, see Login settings.
When you call the
login API (details) to log in, if the limit specified by the multi-client login policy for your account is exceeded, a newly logged in instance will kick out an earlier one.
The one kicked out will receive the onKickedOffline callback (details).Logout
Generally, if your application's lifecycle is the same as the Chat SDK's lifecycle, there is no need to log out before exiting the application.
In special cases, for example, if you use the Chat SDK only after entering a specific UI and no longer use it after exiting the UI, you can call the
logout API (details) to log out of the SDK, after which you will no longer receive new messages. Note that in this case, you also need to call unInitSDK (details) after the logout to uninitialize the SDK.Sample code:
V2TimCallback logoutRes = await TencentImSDKPlugin.v2TIMManager.logout();if(logoutRes.code == 0){}
Account Switch
For example, to switch the logged-in user from
alice to bob, just log bob in. You don't need to explicitly call logout alice, as this operation will be handled automatically inside the Chat SDK.