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>
);
},
});

TabBarIOS 好像是写好的组件