The concept of Shared Preference is android specific and not available in iOS. If you want to save something, I recommend you use Method Channel(Platform Channel) in Flutter to send it to the native layer and save it.
For iOS use userDefaults to save your data.
Additional info:
How to save data using Shared Preference?
SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode
Editor editor = pref.edit();
editor.putBoolean("key_name", true); // Storing boolean - true/false
editor.putString("key_name", "string value"); // Storing string
editor.putInt("key_name", "int value"); // Storing integer
editor.putFloat("key_name", "float value"); // Storing float
editor.putLong("key_name", "long value"); // Storing long
editor.commit(); // Don't forget to commit when your changes are done.
To retrive data
// returns stored preference value
// If value is not present return second param value - In this case null
pref.getString("key_name", null); // getting String
pref.getInt("key_name", null); // getting Integer
pref.getFloat("key_name", null); // getting Float
pref.getLong("key_name", null); // getting Long
pref.getBoolean("key_name", null); // getting boolean
How to save data using userDefaults?
NSString *valueToSave = @"someValue";
[[NSUserDefaults standardUserDefaults] setObject:valueToSave
forKey:@"preferenceName"];
[[NSUserDefaults standardUserDefaults] synchronize];
To retrieve saved data
NSString *savedValue = [[NSUserDefaults standardUserDefaults]
stringForKey:@"preferenceName"];
UPDATE :
There is a flutter plugin which does this for us.
Add this to your pubspec.yaml file
dependencies:
shared_preferences: "^0.4.0"
And run in command line in your project root directory.
$ flutter packages get
Now in your Dart code you can use,
import 'package:shared_preferences/shared_preferences.dart';