Keep a singleton of connectivity monitor in GRPCHost

src/objective-c/GRPCClient/private/GRPCHost.m

@@ -100,10 +100,8 @@ static GRPCConnectivityMonitor *connectivityMonitor = nil;
       _address = address;
       _secure = YES;
       kHostCache[address] = self;
-
+    }
-      // When there is host in the cache, keep a single monitor to the network
+    // Keep a single monitor to flush the cache if the connectivity status changed
-      // to
-      // flush the cache if the connectivity status changed
     if (!connectivityMonitor) {
       connectivityMonitor =
       [GRPCConnectivityMonitor monitorWithHost:hostURL.host];
@@ -114,7 +112,6 @@ static GRPCConnectivityMonitor *connectivityMonitor = nil;
                          wifiStatusChangeHandler:handler];
     }
   }
-  }
   return self;
 }
 
@@ -125,8 +122,6 @@ static GRPCConnectivityMonitor *connectivityMonitor = nil;
                                                     BOOL * _Nonnull stop) {
       [host disconnect];
     }];
-    [kHostCache removeAllObjects];
-    connectivityMonitor = nil;
   }
 }