如何在反應原生 expo 應用程序（android）中授予相機權限

Question

我的代碼是：

import React, { useEffect } from "react";
import * as ImagePicker from "expo-image-picker";

import Screen from "./app/components/Screen";

export default function App() {
  async function permisionFunction() {
    const result = await ImagePicker.getCameraPermissionsAsync();
    if (!result.granted) {
      console.log(result);
      alert("need access to gallery for this app to work");
    }
  }

  useEffect(() => {
    permisionFunction();
  }, []);

  return <Screen></Screen>;
}

第一次提示時，我拒絕了相機的權限。 現在，每當我打開應用程序時，總是need access to gallery for this app to work此消息就會顯示出來。 對於 android。

• 我嘗試在設置中將所有權限授予 expo 應用程序，但仍然出現相同的消息。 我該如何解決這個問題。

Answer 1

使用expo-camera模塊訪問設備攝像頭。

我策划了一個小型應用程序的工作示例，您可以使用它從圖庫和設備相機中訪問圖片。

工作應用程序： Expo 小吃

import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View, Button, Image } from 'react-native';
import { Camera } from 'expo-camera';
import * as ImagePicker from 'expo-image-picker';

export default function Add({ navigation }) {
  const [cameraPermission, setCameraPermission] = useState(null);
  const [galleryPermission, setGalleryPermission] = useState(null);

  const [camera, setCamera] = useState(null);
  const [imageUri, setImageUri] = useState(null);
  const [type, setType] = useState(Camera.Constants.Type.back);

  const permisionFunction = async () => {
    // here is how you can get the camera permission
    const cameraPermission = await Camera.requestPermissionsAsync();

    setCameraPermission(cameraPermission.status === 'granted');

    const imagePermission = await ImagePicker.getMediaLibraryPermissionsAsync();
    console.log(imagePermission.status);

    setGalleryPermission(imagePermission.status === 'granted');

    if (
      imagePermission.status !== 'granted' &&
      cameraPermission.status !== 'granted'
    ) {
      alert('Permission for media access needed.');
    }
  };

  useEffect(() => {
    permisionFunction();
  }, []);

  const takePicture = async () => {
    if (camera) {
      const data = await camera.takePictureAsync(null);
      console.log(data.uri);
      setImageUri(data.uri);
    }
  };

  const pickImage = async () => {
    let result = await ImagePicker.launchImageLibraryAsync({
      mediaTypes: ImagePicker.MediaTypeOptions.Images,
      allowsEditing: true,
      aspect: [1, 1],
      quality: 1,
    });

    console.log(result);
    if (!result.cancelled) {
      setImageUri(result.uri);
    }
  };

  return (
    <View style={styles.container}>
      <View style={styles.cameraContainer}>
        <Camera
          ref={(ref) => setCamera(ref)}
          style={styles.fixedRatio}
          type={type}
          ratio={'1:1'}
        />
      </View>

      <Button title={'Take Picture'} onPress={takePicture} />
      <Button title={'Gallery'} onPress={pickImage} />
      {imageUri && <Image source={{ uri: imageUri }} style={{ flex: 1 }} />}
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
  },
  cameraContainer: {
    flex: 1,
    flexDirection: 'row',
  },
  fixedRatio: {
    flex: 1,
    aspectRatio: 1,
  },
  button: {
    flex: 0.1,
    padding: 10,
    alignSelf: 'flex-end',
    alignItems: 'center',
  },
});

Answer 2

它在文檔配置中提到。

在托管應用中，Camera 需要Permissions.CAMERA 。 視頻錄制需要Permissions.AUDIO_RECORDING 。

Answer 3

我有同樣的問題......我正在使用 expo SDK 42 並且在拒絕回答后權限請求不再觸發。

無論如何，您的代碼中有一些錯誤，您必須查看權限響應的狀態屬性。

這是檢查響應狀態的方法

 const requestPermissions = async () => { try { const { status, } = await ImagePicker.requestMediaLibraryPermissionsAsync(); console.log('status lib', status); setHasPickerPermission(status === 'granted'); } catch (error) { console.log('error', error); } try { const { status } = await ImagePicker.requestCameraPermissionsAsync(); console.log('status camera', status); setHasCameraPermission(status === 'granted'); } catch (error) { console.log('error', error); } }; useEffect(() => { requestPermissions(); }, []);