@interface StringeeClient : NSObjectRepresents a Stringee client, manages the client's connection. This class provides methods to connect to/disconnect from Stringee server, receives the connection's events, the incoming call event.
| userId | 
|---|
| It's the unique identification of the client on Stringee system.  | 
| hasConnected | 
| Whether the client connects to Stringee server:
  | 
| connectionDelegate | 
| A delegate to monitor the connection's events. For more information, see StringeeConnectionDelegate  | 
| incomingCallDelegate | 
| A delegate to monitor when having an incoming call. For more information, see StringeeIncomingDelegate  | 
| - initWithConnectionDelegate: | 
| Creates a new StringeClient instance and registers a connectionDelegate object.  | 
| - connectWithAccessToken: | 
| Connects to Stringee server with an access token.  | 
| - sendCustomMessage:toUserId:completionHandler: | 
| Send a custom message to a user:  | 
| - registerPushForDeviceToken:isProduction:isVoip:completionHandler: | 
|  Register device token to receive push notification. When you have an incoming call, you receive a notification from Stringee server:   | 
| - unregisterPushForDeviceToken:completionHandler: | 
| Remove your device token from Stringee server. Your device will not receive push  notification when you have an incoming call:   | 
| - disconnect: | 
| Disconnects from Stringee server.  |