expo filesystem.readasstringasync无法读取文件

我有以下设置,当用户使用ImagePicker拍照时,它将保存到 FileSystem.documentDirectory 使用以下代码:

saveAvatar = async (uri) => {
   await Expo.FileSystem.moveAsync({
   from: uri,
   to: Expo.FileSystem.documentDirectory + 'avatar/profile'
  })
}

_takePhoto = async () => {
  const result = await ImagePicker.launchCameraAsync({
    allowsEditing: false,
    base64: true,
    quality: 0.4
  });

  if (!result.cancelled) {
    this.setState({ image: result.base64 });
    this.saveAvatar(result.uri)
  }
}; 

然后我试着用这个来检索它:

ensureDirAsync = async () => {
    const props = await FileSystem.getInfoAsync(FileSystem.documentDirectory + 'avatar/');

    if (props.exists && props.isDirectory) {
        return props;
    }

    try {
        await FileSystem.makeDirectoryAsync(FileSystem.documentDirectory + 'avatar/', { intermediates: true });
    }
    catch (e) {
        console.log(e);
    }

    return await this.ensureDirAsync()
}

getAvatar = async () => {
    let dir = await this.ensureDirAsync(),
        filename = await FileSystem.readDirectoryAsync(dir.uri),
        data = null;
    const props = await FileSystem.getInfoAsync(dir.uri + filename[0])
    console.log(props)
    try {
        data = await FileSystem.readAsStringAsync(FileSystem.documentDirectory + 'avatar/profile');
    }
    catch (e) {
        console.log(e);
    }
    console.log(data)
    return data;
}

奇怪的是, const props = await FileSystem.getInfoAsync(dir.uri + filename[0]) 正在打印此:

Object {
 "exists": 1,
 "isDirectory": false,
 "modificationTime": 1532930978,
 "size": 399861,
 "uri": "file:///var/mobile/Containers/Data/Application/9D3661AF-8EB5-49F5-A178-3ECA0F96BEEC/Documents/ExponentExperienceData/%2540anonymous%252FWAMS-1163fc3b-4484-44a2-9076-b4b71df1e55c/avatar/profile",
} 

这应该表明图像保存成功,但是 data = await FileSystem.readAsStringAsync(dir.uri + filename[0]); 或 data = await FileSystem.readAsStringAsync(FileSystem.documentDirectory + 'avatar/profile') 会给我这个错误:

File 'file:///var/mobile/Containers/Data/Application/9D3661AF-8EB5-49F5-A178-3ECA0F96BEEC/Documents/ExponentExperienceData/%2540anonymous%252FWAMS-1163fc3b-4484-44a2-9076-b4b71df1e55c/avatar/profile' could not be read.

你知道怎么会这样吗?可以 FileSystem.readAsStringAsync() 甚至读取我移动的文件 ImagePicker ?如果没有,我应该用什么来代替?

我正在iOS上尝试。

提前感谢您的帮助:笑脸: