added method to obtain whether a session was present

Author: 256dpi

README.md

@@ -245,6 +245,12 @@ Check if the client is currently connected:
 bool connected();
 ```
 
+Check whether a session was present at the time of the last connect:
+
+```c++
+bool sessionPresent();
+```
+
 Configure dropping of overflowing messages (exceeding read buffer):
 
 ```c++

src/MQTTClient.cpp

@@ -371,6 +371,9 @@ bool MQTTClient::connect(const char clientID[], const char username[], const cha
     return false;
   }
 
+  // copy session present flag
+  this->_sessionPresent = options.session_present;
+
   // set flag
   this->_connected = true;
 

src/MQTTClient.h

@@ -72,6 +72,7 @@ class MQTTClient {
   uint16_t keepAlive = 10;
   bool cleanSession = true;
   uint32_t timeout = 1000;
+  bool _sessionPresent = false;
 
   Client *netClient = nullptr;
   const char *hostname = nullptr;
@@ -177,6 +178,7 @@ class MQTTClient {
 
   bool loop();
   bool connected();
+  bool sessionPresent() { return this->_sessionPresent; }
 
   lwmqtt_err_t lastError() { return this->_lastError; }
   lwmqtt_return_code_t returnCode() { return this->_returnCode; }