TabBarIOS.Item报错react.children.only expected to receive a single react element child

使用TabBarIOS.Item，报错如下：

react.children.only expected to receive a single react element child

报错截图

代码如下：

<TabBarIOS.Item systemIcon="bookmarks"
                             selected={this.state.selectedItem === 'page-4'}
                             onPress={()=>this.setState({selectedItem:'page-4'})}>
</TabBarIOS.Item>

报错原因：

TabBarIOS.Item组件必须包含子元素，且子元素必须是一个组件

代码修正如下：

<TabBarIOS.Item systemIcon="bookmarks"
                             selected={this.state.selectedItem === 'page-4'}
                             onPress={()=>this.setState({selectedItem:'page-4'})}>
        <View style={styles.pageStyle}>
            <Text>Page-4</Text>
        </View>
</TabBarIOS.Item>