React Native Text文字显示不全

// 全局设置text组件的fontFamily
import React, { Component } from 'react';　　
import { View, Platform, Text } from 'react-native';　　
  const defaultFontFamily = {　　...Platform.select({　　android: { fontFamily: '' }　　})　　};　　
  const oldRender = Text.render;　　
Text.render = function(...args) {　　
    const origin = oldRender.call(this, ...args);　　
    return React.cloneElement(origin, {　　
       style: [defaultFontFamily, origin.props.style]　　
     });　　
};