I have this error when use SharedPreferences in flutter-CodePudding

Hello I am trying to use SharedPreferences in flutter but this error appears:

NoSuchMethodError: Class 'Future<dynamic>' has no instance method 'setString'.
I/flutter ( 5764): Receiver: Instance of 'Future<dynamic>'

Here is my code:

late SharedPreferences pref;
getPref() async {
  if (pref == null) {
    pref = await SharedPreferences.getInstance();
  } else {
    return pref;
  }
}

getPref.setString("");

CodePudding user response：

"getPref" is a Future function, you need to await it before using "setString" to it.

You can try something like this:

late SharedPreferences pref;
 getPref() async {
      pref = await SharedPreferences.getInstance();
 }

 await getPref();
 pref.setString("MY_KEY", "MY_VALUE");

Just by careful with using the "late" keyword, you should check when using "pref" that the value is correct and well set.

CodePudding user response：

I suggest to maybe do it like this:

SharedPreferences? pref;

Future<bool> setString(String key, String value) async {
  final p = pref ??= await SharedPreferences.getInstance();
  return await p.setString(key, value);
}