appBarWithPopUpMenuItem.dart

AppBar(
        title: Text('McLaren Chat - ${widget.chatID}'),
        actions: <Widget>[
          IconButton(
            icon: Icon(Icons.exit_to_app),
            onPressed: () async {
              await FirebaseAuth.instance.signOut();
              Navigator.pushReplacementNamed(context, '/');
            },
          ),
          PopupMenuButton(
            itemBuilder: (context) {
              return [
                PopupMenuItem(
                  child: Text('Show Food Menu'),
                  value: ['Biryani', 'Khichdi', 'Sabzi', 'Pulav'],
                ),
                PopupMenuItem(
                  child: Text('Show Weekdays'),
                  value: ['Monday', 'Tuesday', 'Wednesday', 'Friday', 'Saturday', 'Sunday'],
                ),
                PopupMenuItem(
                  child: Text('Close All'),
                  value: <String>[],
                )
              ];
            },
            onSelected: (List<String> value) {
              print('Selected value $value');
              setState(() {
                FocusScope.of(context).unfocus();
                options = value.isEmpty ? null : value;
              });
            },
          )
        ],
      )