Navigation Builder Pattern

navigation_builder.dart

/// Platform agnostic navigation definition.
class NavigationItem {
  final Icon icon;
  final String title;
  final VoidCallback onTap;

  NavigationItem({this.icon, this.title, this.onTap});
}

/// Helper for returning platform specific navigation items.
class NavigationMenu {
  final List<NavigationItem> items;

  NavigationMenu({this.items});

  Drawer get drawer {
    if (!Platform.isAndroid) {
      return null;
    }
    return new Drawer(
      child: new ListView(
          children: items
              .map((item) => new ListTile(
                    leading: item.icon,
                    title: new Text(item.title),
                    onTap: item.onTap,
                  ))
              .toList()),
    );
  }

  BottomNavigationBar get bottomBar {
    if (!Platform.isIOS) {
      return null;
    }
    return new BottomNavigationBar(
      items: items
          .map((item) => new BottomNavigationBarItem(
                icon: item.icon,
                title: new Text(item.title),
              ))
          .toList(),
      onTap: (idx) => items[idx].onTap(),
    );
  }
}