The shared_preferences plugin

1. Saving data

There are three primary ways to save data to your device:

1. Write formatted data, like JSON, to a file.

2. Use a library or plugin to write simple data to a shared location

3. Use a SQLite database.

Writing data to a file is simple, but it requires you to handle reading and writing data in the correct format and order.

You can also use a library or plugin to write simple data to a shared location managed by the platform, like iOS and Android. This is what you’ll do in this chapter.

For more complex data, you can save the information to a local database. You’ll learn more about that in future chapters.

2. Why save small bits of data?

There are many reasons to save small bits of data. For example, you could save the user ID when the user has logged in — or if the user has logged in at all. You could also save the search history to consult later.

Note that this simple data saved to a shared location is lost when the user uninstalls the app or clear the app data and cache.

3. The shared_preferences plugin

shared_preferences is a Flutter plugin that allows you to save data in a key-value format so you can easily retrieve it later. Behind the scenes, it uses the aptly named SharedPreferences on Android and the similar UserDefaults on iOS.

For the app 4, you’ll learn to use the plugin by saving the Best Score and for the app 8, by saving the favorite movies.

One of the great things about this plugin is that it doesn’t require any setup or configuration. Just create an instance of the plugin and you’re ready to fetch and save data.

shared_preferences - pub.dev