Using the GetTotalUnreadMessageCount() method, you can retrieve the total number of a user's unread messages in all group channels the user has joined.
SbGroupChannelTotalUnreadMessageCountParams unreadMessageCountParams = new SbGroupChannelTotalUnreadMessageCountParams();
SendbirdChat.GroupChannel.GetTotalUnreadMessageCount(unreadMessageCountParams, (inGroupChannelCount, inFeedChannelCount, inError) =>
{
if (inError != null)
return; // Handle error.
// Further actions or processing using inGroupChannelCount and inFeedChannelCount if necessary.
});