feat(add CupertinoTabBar demo):

lib/widgets/components/Bar/SliverAppBar/demo.dart

@@ -48,7 +48,7 @@ class SliverAppBarLessDefault extends StatelessWidget {
     }
     return new SizedBox(
         height: 500.0,
-        child:NestedScrollView(
+        child: NestedScrollView(
           headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
             return <Widget>[
               SliverAppBar(

lib/widgets/themes/Cupertino/CupertinoTabBar/demo.dart

@@ -0,0 +1,53 @@
+/**
+ * Created with Android Studio.
+ * User: 三帆
+ * Date: 20/01/2019
+ * Time: 22:28
+ * email: sanfan.hx@alibaba-inc.com
+ * tartget:  CupertinoTabBar
+ */
+
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/material.dart';
+
+class CupertinoTabBarDemo extends StatefulWidget {
+  _Demo createState() => _Demo();
+}
+
+class _Demo extends State<CupertinoTabBarDemo> {
+  int index = 0;
+
+  changeIndex(int _index) {
+    this.setState(() {
+      index = _index;
+    });
+  }
+  Widget build(BuildContext context) {
+    return Container(
+      height: 500,
+      child: Scaffold(
+          appBar: AppBar(title: const Text('CupertinoTabBarDemo')),
+          floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
+          body: Center(
+            child: Text('CupertinoTabBarDemo in bottom'),
+          ),
+          bottomNavigationBar: CupertinoTabBar(
+            backgroundColor: Color.fromRGBO(244, 244, 244, 0.5),
+            currentIndex: index,
+            onTap: (i) {
+              this.changeIndex(i);
+            },
+            items: [
+              BottomNavigationBarItem(
+                title: Text("1"),
+                icon: Icon(Icons.add),
+              ),
+              BottomNavigationBarItem(
+                  title: Text("2"),
+                  icon: Icon(Icons.delete)
+              )],
+          )
+      ),
+    );
+  }
+}

lib/widgets/themes/Cupertino/CupertinoTabBar/index.dart

@@ -0,0 +1,44 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_go/common/widget_demo.dart';
+import 'package:flutter_go/widgets/themes/Material/MaterialColor/demo.dart';
+import 'demo.dart';
+const Text0 = '''
+### **简介**
+> ios风格下底部导航组件.
+
+通过BottomNavigationBarItem列表,在屏幕底部展示多个小组件,  默认下选择第一个小组件;
+
+### **基本用法**
+
+这个组件, 没有任何内部状态, 使用时需要开发者自己去监听**onTap**方法, 主动为组件的属性**currentIndex**赋值
+
+在官网上有这么一段文字:
+
+> If the given backgroundColor's opacity is not 1.0 (which is the case by default), it will produce a blurring effect to the content behind it.
+
+本人试了很多次. 也没有发现这个Blur Effect是怎么触发的, 如果有人了解, 欢迎提PR.
+''';
+
+
+class Demo extends StatefulWidget {
+  static const String routeName =
+      '/element/themes/Cupertino/CupertinoTabBar';
+
+  @override
+  State<StatefulWidget> createState() => _DemoState();
+}
+
+class _DemoState extends State<Demo> {
+  @override
+  Widget build(BuildContext context) {
+    return WidgetDemo(
+      title: 'CupertinoTabBar',
+      codeUrl: '/themes/Cupertino/CupertinoTabBar/demo.dart',
+      docUrl: 'https://docs.flutter.io/flutter/cupertino/CupertinoTabBar-class.html',
+      contentList: [
+        Text0,
+        CupertinoTabBarDemo()
+      ],
+    );
+  }
+}

lib/widgets/themes/Cupertino/index.dart

@@ -5,6 +5,7 @@ import './CupertinoSlider/index.dart' as CupertinoSlider;
 import './CupertinoSegmentedControl/index.dart' as CupertinoSegmentedControl;
 import './CupertinoSliverNavigationBar/index.dart' as CupertinoSliverNavigationBar;
 import './CupertinoSwitch/index.dart' as CupertinoSwitch;
+import './CupertinoTabBar/index.dart' as CupertinoTabBar;
 List<WidgetPoint> widgetPoints = [
   WidgetPoint(
     name: 'CupertinoScrollbar',
@@ -36,4 +37,9 @@ List<WidgetPoint> widgetPoints = [
     routerName: CupertinoSwitch.Demo.routeName,
     buildRouter: (BuildContext context) => CupertinoSwitch.Demo(),
   ),
+  WidgetPoint(
+    name: 'CupertinoTabBar',
+    routerName: CupertinoTabBar.Demo.routeName,
+    buildRouter: (BuildContext context) => CupertinoTabBar.Demo(),
+  ),
 ];

pubspec.yaml

@@ -167,6 +167,7 @@ flutter:
     - lib/widgets/themes/Cupertino/CupertinoSlider/demo.dart
     - lib/widgets/themes/Cupertino/CupertinoSegmentedControl/demo.dart
     - lib/widgets/themes/Cupertino/CupertinoSwitch/demo.dart
+    - lib/widgets/themes/Cupertino/CupertinoTabBar/demo.dart
     - assets/app.db
     - assets/images/
     - lib/common/example_code_parser.dart