To create a group, call the below method.
|groupName||Name of the group (cannot be null or empty)|
|participantJidList||Array of jids of the member (size cannot be less than 2 excluding group creator)|
|groupImageFileUrl||local file url of the image (can be empty)|
|completionHandler||implemented as closure expression|
Note: Even if you don't have internet connection, you are still allowed to send messages which will be kept in offline database.Once the user connected to the internet, the messages will be sent automatically when user opens the app.