flutter - 如何将Future Dynamic转换为String？

Question

我正在遵循旧教程，并且在最后一行代码中出现有关ImageUrl的错误:
“不能将 future 动态分配给参数类型String”。
我该如何解决？

class _MyAppState extends State<MyApp> {

  static FirebaseStorage storage = FirebaseStorage(
    storageBucket: 'gs://natapp-7d2db/storage/natapp-7d2db.appspot.com/files'
  );

  static StorageReference imageRef = storage.ref().child('cake.png');

  final imageUrl = imageRef.getDownloadURL();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(brightness: Brightness.dark),
      home: Container(
        child: Image.network(imageUrl),
      ),
    );
  }
}

编辑:我用过

child: Image.network(imageUrl.toString)

Answer 1

用Use Container替换FutureBuilder，因为FutureBuilder是一个小部件，用于在Future上运行的异步回调

FutureBuilder<String>(
      future: imageRef.getDownloadURL(),
      builder: (context, snapshot) {
        if (snapshot.hasData) {
           return Container(
                child: Image.network(snapshot.data));
        }

        if (snapshot.hasError) return WidgetThatShowsError();

        // by default show progress because operation is async and we need to wait for result
        return CircularProgressIndicator();
      },
    );