Скачать или смотреть How to Delete Data After Specified Time in Flutter Without Restarting the Timer

Learn how to manage data deletion in your Flutter app using SharedPreferences with a timer that persists through app closures. Find out how to ensure the timer continues even when the app is reopened.
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This video is based on the question https://stackoverflow.com/q/76299137/ asked by the user 'Md. Samiul Islam' ( https://stackoverflow.com/u/19111658/ ) and on the answer https://stackoverflow.com/a/76299253/ provided by the user 'Thanh' ( https://stackoverflow.com/u/19205549/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Managing Data Deletion Timing in Flutter: A Guide

When developing a Flutter application, one common challenge developers face is managing data persistence effectively. A particularly interesting scenario involves timing data deletion, where the data needs to be discarded after a specified duration, say 5 minutes. However, if the app is closed midway through that period, you want the timer to continue rather than restart from scratch. In this guide, we will explore how to implement this feature using SharedPreferences, along with a timer that retains its state even after the app is closed and reopened.

The Problem

You’ve created a Flutter app that saves user data in SharedPreferences. Once the data is saved, the app is expected to start a timer for 5 minutes. After this period, the data should be removed, and the user should be navigated back to the login page. Here is the catch: if the user closes the app halfway through the timer (for example, after 2 minutes and 30 seconds), the timer should not reset when they reopen the app. It should continue from where it left off.

Understanding the Solution

To achieve this, we will utilize the app lifecycle management tools provided by Flutter. Below are the key steps we'll follow:

Listen for App State Changes: By observing app lifecycle states, we can detect when the app goes into the background (paused) and when it returns to the foreground (resumed).

Utilize SharedPreferences for Timing: We will store the remaining time in SharedPreferences when the app is paused, and retrieve it when the app is resumed to continue the timer.

Step-by-Step Implementation

1. Initialize SharedPreferences

Initially, we need to set up our SharedPreferences to save the necessary data. This includes the current time when the user starts the timer.

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2. Track Application Lifecycle

Next, we will implement the WidgetsBindingObserver to listen for app state changes. This will help us determine when to pause and resume the timer.

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3. Handle Remaining Time

Now, you'll want to create methods to save and retrieve the remaining time:

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Conclusion

By following these steps, you'll be able to manage the timer for your data deletion in Flutter seamlessly. The key takeaway is to leverage the app lifecycle to pause and resume the timer while using SharedPreferences to remember the remaining time. This will provide a smooth user experience without unexpected resets of the timer when the app is opened again.

With this implementation, your Flutter application can effectively handle data expiration in a user-friendly manner, ensuring users are navigated appropriately even after closing the app. Happy coding!