TYPESCRIPT

react native elements button with icon

<Button
  icon={
    <Icon
      name="arrow-right"
      size={15}
      color="white"
    />
  }
  title="Button with icon component"
/>

button with icon react native ui

import FontAwesome from "react-native-vector-icons/FontAwesome";
import { Text, TouchableOpacity } from "react-native";

<TouchableOpacity
	style={{ borderRadius:5, paddingVertical:10, paddingHorizontal:30, flexDirection: 'row', backgroundColor: '#3578E5' }}
	onPress={() => this.signInFacebook(context.updateAuthUser)}>
  	<FontAwesome name='facebook' size={20} color='#fff' />
    <Text style={{ marginLeft: 10, color: '#fff', fontWeight: 'bold' }}>
      Login With Facebook 
	</Text>
</TouchableOpacity>