How to Use SharedPreferences in Flutter for Persistent Data Storage

Learn how to effectively utilize `SharedPreferences` in your Flutter app to store and retrieve persistent data, ensuring your app behaves consistently across sessions.
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Mastering SharedPreferences in Flutter

When developing a Flutter application, one common requirement is the need to persist data across sessions. A frequent request from developers is, "How do I use SharedPreferences in Flutter to maintain my app's state?" If you find it challenging, especially with something like a stars counter that should retain its value even after the app is closed, don't worry—this guide will guide you through the solution.

Understanding the Problem

Imagine creating a quiz app where users earn stars based on correct answers. Naturally, you want the stars counted to remain the same, regardless of whether the app is relaunched. The fundamental issue here is that local variables lose their values when the app is closed.

In your provided code, you’ve started implementing a counter using an integer variable, but you're encountering a challenge: the stars count resets to zero each time the app starts.

Analyzing the Solution

The solution involves leveraging SharedPreferences, a persistent storage solution for primitive data types in Flutter, to store and retrieve your stars count. Let's break it down into clear steps.

Step 1: Initialize SharedPreferences

Here’s how to properly implement this in your Flutter app:

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With this setup, you have a single instance of SharedPreferences that can be accessed throughout your app.

Step 2: Save and Update Stars Count

In the updateStarsNumber function, you need to ensure that you're updating the value correctly. Instead of initializing SharedPreferences each time, use the instance created in main.

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Step 3: Retrieve Stars Count

When you want to access the stars count, for instance in your ProfilePage, you can easily retrieve it using the same prefs instance.

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Step 4: Integrate with Your Game Logic

Whenever a user correctly guesses in your game, call the updateStarsNumber function to keep the stars count updated.

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Conclusion

By following these steps, you can effectively use SharedPreferences to maintain a consistent state in your Flutter app. Ensuring you initialize your SharedPreferences instance globally and updating the stars count correctly will allow your users to see their progress persist across app launches.

Incorporating persistent storage can significantly enhance user experience by maintaining continuity, and SharedPreferences is a powerful tool for achieving that in Flutter. Start implementing this in your projects today and enhance your Flutter app's functionality!