Keep a singleton of connectivity monitor in GRPCHost

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

@@ -100,19 +100,16 @@ 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
+    if (!connectivityMonitor) {
-      // flush the cache if the connectivity status changed
+      connectivityMonitor =
-      if (!connectivityMonitor) {
+      [GRPCConnectivityMonitor monitorWithHost:hostURL.host];
-        connectivityMonitor =
+      void (^handler)() = ^{
-            [GRPCConnectivityMonitor monitorWithHost:hostURL.host];
+        [GRPCHost flushChannelCache];
-        void (^handler)() = ^{
+      };
-          [GRPCHost flushChannelCache];
+      [connectivityMonitor handleLossWithHandler:handler
-        };
+                         wifiStatusChangeHandler:handler];
-        [connectivityMonitor handleLossWithHandler:handler
-                           wifiStatusChangeHandler:handler];
-      }
     }
   }
   return self;
@@ -125,8 +122,6 @@ static GRPCConnectivityMonitor *connectivityMonitor = nil;
                                                     BOOL * _Nonnull stop) {
       [host disconnect];
     }];
-    [kHostCache removeAllObjects];
-    connectivityMonitor = nil;
   }
 }