可能未處理的 promise Rejection (id:0) React Native

Question

有錯誤，不知道這里有什么問題。 任何想法？ 我需要得到經度和緯度。 請告訴我 Expo 創建的 react native 項目是否還有其他好的方法。 謝謝！

import { StatusBar } from 'expo-status-bar';
import { StyleSheet, Text, View } from 'react-native';
import { Location, Permissions } from 'expo';
import React from 'react';

export default class App extends React.Component{

  state = {
    location: {},
    erroMessage: '',
  }

  componentWillMount(){
    this._getLocation();
  }

  _getLocation = async () => {
    const { status } = await Permissions.askAsync(Permissions.LOCATION);

    if(status !== 'granted'){
      console.log('PERMISSION NOT GRANTED!');

      this.setState({
        erroMessage: 'PERMISSIN NOT GRANTED'
      })
    }

    const location = await Location.getCurrentPositionAsync();

    this.setState({
      location,
    });

  };

  render () {
    return (
      <View style={styles.container}>
        <Text>{JSON.stringify(this.state.location)}</Text>
        <StatusBar style="auto" />
      </View>
    );
  }
}

Answer 1

對於來自Permissions.askAsync和Location.getCurrentPositionAsync的 Promise，您沒有任何錯誤處理。 將等待的函數包裝在try / catch塊中並處理來自error塊的任何錯誤。

_getLocation = async () => {
  try {
    const { status } = await Permissions.askAsync(Permissions.LOCATION);

    if(status !== 'granted'){
      console.log('PERMISSION NOT GRANTED!');

      this.setState({
        erroMessage: 'PERMISSIN NOT GRANTED'
      });
    }

    const location = await Location.getCurrentPositionAsync();

    this.setState({
      location,
    });
  } catch (error) {
    // Handle any errors here.
  }
};

Answer 2

您還需要添加else條件。 如果未授予權限，請停止執行或再次請求權限。

_getLocation = async () => {
try {
    const { status } = await Permissions.askAsync(Permissions.LOCATION);

    if (status !== 'granted') {
        console.log('PERMISSION NOT GRANTED!');

        this.setState({
            erroMessage: 'PERMISSIN NOT GRANTED',
        });
    } else {
        const location = await Location.getCurrentPositionAsync();

        this.setState({
            location,
        });
    }
} catch (error) {
    // Handle any errors here.
}

};