fix(phone-as-device): app-478 app-479 fix NPE client is non connected

README.md

@@ -128,6 +128,14 @@ To handle messages in the subscribed topic, you have to handle a [`receive-messa
 MqttClient.disconnect();
 ```
 
+### Check if client is connected to an MQTT Broker
+
+`MqttClient.isConnected` checks if client is connected to an MQTT Broker.
+
+```js
+MqttClient.isConnected();
+```
+
 ### Loading an identity
 
 An identity stored in a device specific key store by `MqttClient.setIdentity` may be loaded by `MqttClient.loadIdentity`.

android/src/main/java/com/github/emotokcak/reactnative/mqtt/RNMqttClient.kt

@@ -537,6 +537,31 @@ class RNMqttClient(reactContext: ReactApplicationContext)
         }
     }
 
+    /**
+     * Determines if this client is currently connected to the server.
+     * Returns: true if connected, false otherwise.
+     *
+     * @param promise
+     *
+     *   Resolved when check connection has done.
+     */
+    @ReactMethod
+    fun isConnected(promise: Promise) {
+        val client = this.client
+        if (client == null) {
+            promise.resolve(false)
+            return
+        }
+        try {
+            val isClientConnected = client.isConnected
+            promise.resolve(isClientConnected)
+        } catch (e: Exception) {
+            Log.e(NAME, "failed to check connection", e)
+            promise.reject("ERROR_CHECK_CONNECTION", e)
+            return
+        }
+    }
+
     // Notifies a `got-error` event.
     private fun notifyError(code: String, cause: Throwable?) {
         val params = Arguments.createMap()

ios/MqttClient.m

@@ -12,6 +12,8 @@ @interface RCT_EXTERN_MODULE(MqttClient, NSObject)
 
 RCT_EXTERN_METHOD(connect:(NSDictionary*)params resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
 
+RCT_EXTERN_METHOD(isConnected:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)
+
 RCT_EXTERN_METHOD(disconnect)
 
 RCT_EXTERN_METHOD(publish:(NSString*)topic payload:(NSArray*)payload resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)

ios/MqttClient.swift

@@ -324,7 +324,30 @@ class MqttClient : RCTEventEmitter {
         _ = self.client!.connect()
         resolve(nil)
     }
-
+
+    @objc(isConnected:reject:)
+    func isConnected(resolve: RCTPromiseResolveBlock, reject: RCTPromiseRejectBlock) -> Void
+    {
+        os_log("MqttClient: isConnected")
+        guard let client = self.client else {
+            resolve(false)
+            return
+        }
+        var isConnected: Bool
+        let connectionState = client.connState
+        switch connectionState {
+        case .connected:
+            isConnected = true
+        case .connecting:
+            isConnected = false
+        case .disconnected:
+            isConnected = false
+        default:
+            isConnected = false
+        }
+        resolve(isConnected)
+    }
+
     @objc(disconnect)
     func disconnect() -> Void {
         os_log("MqttClient: disconnecting")

package.json

@@ -1,6 +1,6 @@
 {
   "name": "react-native-mqtt-client",
-  "version": "0.2.0",
+  "version": "0.2.1",
   "description": "MQTT client for React Native",
   "main": "lib/commonjs/index",
   "module": "lib/module/index",

src/index.tsx

@@ -182,6 +182,19 @@ export class MqttClient {
     return MqttClientImpl.subscribe(topic);
   }
 
+  /**
+   * Determines if this client is currently connected to the server
+   *
+   * @function isConnected
+   *
+   * @return {Promise<boolean>}
+   *
+   *   Resolved when check connection has done.
+   */
+  isConnected(): Promise<boolean> {
+    return MqttClientImpl.isConnected();
+  }
+
   /**
    * Listens for a given event from this client.
    *