React-Native 获取屏幕尺寸

XCODE补充
启动项目：react-native init 项目名称

修改Xcode中plist文件：
<key>NSAppTransportSecurity</key>
    <dict>
        <key>NSAllowsArbitraryLoads</key>
        <true/>
    </dict>
否则，连接不到服务器

var Dimensions = require('Dimensions');
var ScreenWidth = Dimensions.get('window').width;
var ScreenHeight = Dimensions.get('window').height;
var ScreenScale = Dimensions.get('window').scale;

export default class rn extends Component {
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Welcome to React Native!
        </Text>
        <Text style={styles.screenStyle}>
            {ScreenWidth} * {ScreenHeight} : {ScreenScale} //别忘记加{}
        </Text>

      </View>
    );
  }
}