You can check if a user in the Sendbird application is currently connected to the Sendbird server. For group channels only, you can check whether each member is currently connected to the server.
final query = ApplicationUserListQuery()
..userIdsFilter = ['Tyler'];
try {
final users = await query.next();
// user[0] is Tyler.
if (users.first.connectionStatus == UserConnectionStatus.online) {
// Tyler is currently online.
// UserConnectionStatus consists of online, offline, and notAvailable.
}
} catch (e) {
// Handle error.
}