add multiplr_conversation example

lib/src/channel_list_view.dart

@@ -100,14 +100,15 @@ class _ChannelListViewState extends State<ChannelListView> {
 
       Widget child;
       if (widget._channelPreviewBuilder != null) {
-        child = widget._channelPreviewBuilder(context, channelState);
+        child = GestureDetector(
+          onTap: () {
+            widget.onChannelTap(channelClient);
+          },
+          child: widget._channelPreviewBuilder(context, channelState),
+        );
       } else {
         child = ChannelPreview(
-          onTap: widget?.onChannelTap != null
-              ? () {
-                  widget?.onChannelTap(channelClient);
-                }
-              : null,
+          onTap: widget.onChannelTap,
         );
       }
 

lib/src/channel_preview.dart

@@ -4,12 +4,13 @@ import 'package:flutter/widgets.dart';
 import 'package:stream_chat/stream_chat.dart';
 
 import 'channel_image.dart';
+import 'channel_list_view.dart';
 import 'channel_name_text.dart';
 import 'stream_channel.dart';
 import 'stream_chat.dart';
 
 class ChannelPreview extends StatelessWidget {
-  final VoidCallback onTap;
+  final ChannelTapCallback onTap;
 
   const ChannelPreview({
     Key key,
@@ -37,14 +38,13 @@ class ChannelPreview extends StatelessWidget {
     ChannelState channelState,
     StreamChannelState streamChannel,
   ) {
+    final channelClient =
+        StreamChat.of(context).client.channelClients[channelState.channel.id];
     return StreamChannel(
-      channelClient:
-          StreamChat.of(context).client.channelClients[channelState.channel.id],
+      channelClient: channelClient,
       child: ListTile(
         onTap: () {
-          if (onTap != null) {
-            onTap();
-          }
+          onTap(channelClient);
         },
         leading: ChannelImage(
           channel: channelState.channel,

lib/src/stream_channel.dart

@@ -8,7 +8,7 @@ class StreamChannel extends StatefulWidget {
   StreamChannel({
     Key key,
     @required this.child,
-    this.channelClient,
+    @required this.channelClient,
   }) : super(
           key: key,
         );
@@ -95,8 +95,6 @@ class StreamChannelState extends State<StreamChannel> {
   @override
   void dispose() {
     _queryMessageController.close();
-    widget.channelClient.dispose();
-
     super.dispose();
   }
 
@@ -109,6 +107,7 @@ class StreamChannelState extends State<StreamChannel> {
     }
     return FutureBuilder<bool>(
       future: widget.channelClient.initialized,
+      initialData: widget.channelClient.state != null,
       builder: (context, snapshot) {
         if (!snapshot.hasData) {
           return Scaffold(