Fix untilAttach examples to contain subscribe

Author: GregHolmes

src/pages/docs/storage-history/history.mdx

@@ -444,7 +444,12 @@ Use the `untilAttach` option when making history requests on attached channels.
 const realtime = new Ably.Realtime('{{API_KEY}}');
 const channel = realtime.channels.get('{{RANDOM_CHANNEL_NAME}}');
 await channel.publish('example', 'message data');
-await channel.attach();
+
+channel.subscribe((message) => {
+    console.log('Received message: ' + message.data);
+});
+
+await channel.whenState('attached');
 
 const history = await channel.history({untilAttach: true});
 const lastMessage = history.items[0];
@@ -455,7 +460,12 @@ console.log('Last message before attach: ' + lastMessage.data);
 const realtime = new Ably.Realtime('{{API_KEY}}');
 const channel = realtime.channels.get('{{RANDOM_CHANNEL_NAME}}');
 await channel.publish('example', 'message data');
-await channel.attach();
+
+channel.subscribe((message) => {
+    console.log('Received message: ' + message.data);
+});
+
+await channel.whenState('attached');
 
 const history = await channel.history({untilAttach: true});
 const lastMessage = history.items[0];
@@ -465,7 +475,12 @@ console.log('Last message before attach: ' + lastMessage.data);
 ```realtime_ruby
   realtime = Ably::Realtime.new('{{API_KEY}}')
   channel = realtime.channels.get('{{RANDOM_CHANNEL_NAME}}')
-  channel.attach do
+
+  channel.subscribe do |message|
+    puts "Received message: #{message.data}"
+  end
+
+  channel.on(:attached) do
     channel.history(until_attach: true) do |result_page|
       last_message = result_page.items.last
       puts "Last message before attach: #{last_message.data}")
@@ -476,6 +491,14 @@ console.log('Last message before attach: ' + lastMessage.data);
 ```realtime_java
   AblyRealtime realtime = new AblyRealtime("{{API_KEY}}");
   Channel channel = realtime.channels.get("{{RANDOM_CHANNEL_NAME}}");
+
+  channel.subscribe(new MessageListener() {
+      @Override
+      public void onMessage(Message message) {
+          System.out.println("Received message: " + message.data);
+      }
+  });
+
   channel.on(ChannelState.attached, new ChannelStateListener() {
       @Override
       public void onChannelStateChanged(ChannelStateChange stateChange) {
@@ -490,37 +513,49 @@ console.log('Last message before attach: ' + lastMessage.data);
           }
       }
   });
-
-  channel.attach();
 ```
 
 ```realtime_csharp
   AblyRealtime realtime = new AblyRealtime("{{API_KEY}}");
   IRealtimeChannel channel = realtime.Channels.Get("{{RANDOM_CHANNEL_NAME}}");
-  await channel.AttachAsync();
+
+  channel.Subscribe(message => {
+    Console.WriteLine("Received message: " + message.Data);
+  });
+
+  await channel.WaitForAttachAsync();
+
   PaginatedResult<Message> resultPage = await channel.HistoryAsync(untilAttach: true);
   Message lastMessage = resultPage.Items[0];
-  Console.WriteLine("Last message before attach: " + lastMessage.data);
+  Console.WriteLine("Last message before attach: " + lastMessage.Data);
 ```
 
 ```realtime_objc
 ARTRealtime *realtime = [[ARTRealtime alloc] initWithKey:@"{{API_KEY}}"];
 ARTRealtimeChannel *channel = [realtime.channels get:@"RANDOM_CHANNEL_NAME"];
-[channel attach];
+
+[channel subscribe:^(ARTMessage *message) {
+    NSLog(@"Received message: %@", message.data);
+}];
+
 [channel on:ARTChannelEventAttached callback:^(ARTErrorInfo *error) {
     ARTRealtimeHistoryQuery *query = [[ARTRealtimeHistoryQuery alloc] init];
     query.untilAttach = YES;
     [channel history:query callback:^(ARTPaginatedResult<ARTMessage *> *resultPage, ARTErrorInfo *error) {
         ARTMessage *lastMessage = resultPage.items[0];
-        NSLog(@"Last message: %@ - %@", lastMessage.id,lastMessage.data);
+        NSLog(@"Last message before attach: %@ - %@", lastMessage.id, lastMessage.data);
     } error:nil];
 }];
 ```
 
 ```realtime_swift
 let realtime = ARTRealtime(key: "{{API_KEY}}")
 let channel = realtime.channels.get("{{RANDOM_CHANNEL_NAME}}")
-channel.attach()
+
+channel.subscribe { message in
+    print("Received message: \(message.data)")
+}
+
 channel.on(.attached) { error in
     let query = ARTRealtimeHistoryQuery()
     query.untilAttach = true
@@ -538,24 +573,26 @@ if err != nil {
   log.Fatalf("Failed to create Ably Realtime client: %v", err)
 }
 
-// Get the channel
 channel := client.Channels.Get("{{RANDOM_CHANNEL_NAME}}")
 
-// Publish a message
-err = channel.Publish(context.Background(), "example", "message data")
+unsubscribe, err := channel.Subscribe(context.Background(), func(msg *ably.Message) {
+  fmt.Printf("Received message: %v\n", msg.Data)
+})
 if err != nil {
-  log.Fatalf("Failed to publish message: %v", err)
+  log.Fatalf("Failed to subscribe: %v", err)
 }
+defer unsubscribe()
 
-// Attach the channel
-_ = channel.Attach(context.Background())
+err = channel.Attach(context.Background())
+if err != nil {
+  log.Fatalf("Failed to attach: %v", err)
+}
 
-// Get channel history until attach
 history, _ := channel.HistoryUntilAttach()
 pages, _ := history.Pages(context.Background())
 for pages.Next(context.Background()) {
   for _, message := range pages.Items() {
-    fmt.Println(message)
+    fmt.Printf("Last message before attach: %v\n", message.Data)
   }
 }
 ```
@@ -568,7 +605,12 @@ final realtime = ably.Realtime(options: clientOptions);
 final channel = realtime.channels.get(
   '{{RANDOM_CHANNEL_NAME}}'
 );
-await channel.publish(name: 'example', data: 'message data');
+
+final channelMessageSubscription = channel.subscribe()
+  .listen((message) {
+    print('Received message: ${message.data}');
+  });
+
 await channel.attach();
 
 final historyParams = ably.RealtimeHistoryParams(untilAttach: true);