图片未显示在手机上，但显示在模拟器上

Question

在我的Flutter应用程序中，（Github link here）出现一些不一致的行为。当我在模拟器中运行该应用程序时，我可以从图像库中选择一个图像（使用 image_picker 包），然后在屏幕上显示我选择的图像。

但是，当我构建应用程序并将.apk文件安装到手机上时，从画廊中选择图像后，图像只会显示为空白白色。

“ dora the Explorer gif”应该位于图像的后面。

import 'dart:io';
import 'dart:async';
import 'package:ShowPhotoLock/core/constants/app_strings.dart';
import 'package:ShowPhotoLock/core/viewmodels/views/baseWidget.dart';
import 'package:ShowPhotoLock/core/viewmodels/views/drawer/drawerOnly.dart';
import 'package:ShowPhotoLock/core/viewmodels/views/home/homeScreenViewModel.dart';
import 'package:ShowPhotoLock/core/viewmodels/widgets/photoViewWrapper.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:provider/provider.dart';

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  Future<File> _imageFile;

  pickImageFromGallery(ImageSource source) {
    setState(() {
      _imageFile = ImagePicker.pickImage(source: source);
    });
  }

  Widget showImage() {
    return FutureBuilder<File>(
      future: _imageFile,
      builder: (BuildContext context, AsyncSnapshot<File> snapshot) {
        if (snapshot.connectionState == ConnectionState.done &&
            snapshot.data != null) {
              return Center(child: Image.file(snapshot.data, width: 300, height: 300));
        } else if (snapshot.error != null) {
          return const Text(
            'Error Picking Image',
            textAlign: TextAlign.center,
          );
        }
        return Center(
           child: Text( 'No Image',
            style: Theme.of(context).textTheme.body1)
          );
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return BaseWidget<HomeScreenViewModel>(
      model: HomeScreenViewModel(sharedPreferencesService: Provider.of(context)), 
      builder: (context, model, child) => Scaffold(
      appBar: AppBar(
        title: Text(
          'Show Photo Lock',
          style: Theme.of(context).textTheme.headline,
        ),
      ),
      drawer: _imageFile == null ? DrawerOnly() : null,
      body:  _imageFile == null ? Container() : showImage(),
      floatingActionButton: _imageFile == null
          ? FloatingActionButton(
              onPressed: () {
                pickImageFromGallery(ImageSource.gallery);
              },
              tooltip: 'Pick Image',
              child: Icon(Icons.photo_library),
              backgroundColor: Theme.of(context).primaryColor,
            )
          : Container(),
    ));
  }
}

应用程序在模拟器上可以正常运行：

应用在实际手机上无法正常运行：