R-N很嗨啊，求自定义上下Bar的实例

看到有人做，试着写了个首页，但Docs里没找到自定义Bar样式的方法。

markdown不熟练，搞了半天终于把图片缩小了。

These components are easily incorporated into your app using their React component counterparts, such as TabBarIOS and NavigatorIOS.

var React = require('react-native');
var { TabBarIOS, NavigatorIOS } = React;

var App = React.createClass({
 render: function() {
   return (
     <TabBarIOS>
       <TabBarIOS.Item title="React Native" selected={true}>
         <NavigatorIOS initialRoute={{ title: 'React Native' }} />
       </TabBarIOS.Item>
     </TabBarIOS>
   );
 },
});