Hide/Show searchBar on channel list scroll

Signed-off-by: Sahil Kumar <[email protected]>

example/lib/main.dart

@@ -457,14 +457,17 @@ class _ChannelListPageState extends State<ChannelListPage> {
       },
       child: ChannelsBloc(
         child: MessageSearchBloc(
-          child: Column(
+          child: NestedScrollView(
-            children: [
+            floatHeaderSlivers: true,
-              SearchTextField(
+            headerSliverBuilder: (_, __) => [
+              SliverToBoxAdapter(
+                child: SearchTextField(
                   controller: _controller,
                   showCloseButton: _isSearchActive,
                 ),
-              Expanded(
+              ),
-                child: AnimatedSwitcher(
+            ],
+            body: AnimatedSwitcher(
               duration: const Duration(milliseconds: 350),
               child: GestureDetector(
                 behavior: HitTestBehavior.opaque,
@@ -492,8 +495,7 @@ class _ChannelListPageState extends State<ChannelListPage> {
                                 physics: AlwaysScrollableScrollPhysics(),
                                 child: ConstrainedBox(
                                   constraints: BoxConstraints(
-                                        minHeight:
+                                    minHeight: viewportConstraints.maxHeight,
-                                            viewportConstraints.maxHeight,
                                   ),
                                   child: Center(
                                     child: Column(
@@ -554,8 +556,7 @@ class _ChannelListPageState extends State<ChannelListPage> {
                         ),
                         channelWidget: ChannelPage(),
                         onViewInfoTap: (channel) {
-                              if (channel.memberCount == 2 &&
+                          if (channel.memberCount == 2 && channel.isDistinct) {
-                                  channel.isDistinct) {
                             Navigator.push(
                               context,
                               MaterialPageRoute(
@@ -583,8 +584,6 @@ class _ChannelListPageState extends State<ChannelListPage> {
               ),
             ),
           ),
-            ],
-          ),
         ),
       ),
     );