Скачать или смотреть Solving Flutter's NoInternet Loading Issue on Your Login Page

Learn how to effectively manage loading states in your Flutter app to handle internet connectivity checks seamlessly.
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This video is based on the question https://stackoverflow.com/q/77723150/ asked by the user 'Soumen Pramanik' ( https://stackoverflow.com/u/10406734/ ) and on the answer https://stackoverflow.com/a/77769228/ provided by the user 'Pratik Lakhani' ( https://stackoverflow.com/u/19269162/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving Flutter's NoInternet Loading Issue on Your Login Page

When developing a mobile application using Flutter, ensuring a smooth user experience is crucial, especially during critical actions like logging in. A common problem that many new Flutter developers encounter is effectively managing loading states, particularly when checking for internet connectivity. In this guide, we will address the issue of a NoInternet widget flashing on the screen momentarily before the actual result is determined, providing you with an easy-to-implement solution.

Understanding the Problem

You may have created a Login page in Flutter and want to display a loading indicator while checking for internet access. However, you notice that the NoInternet widget is rendered for a short time even when internet access is present. This can lead to confusion for your users, who may interpret it as a connectivity issue.

The Symptoms

Unnecessary Flickering: The NoInternet widget appears briefly before your app determines if the device has an active internet connection.

User Experience: This flicker can unsettle users and is not an ideal way to display connectivity status.

Layout of the Initial Code

To identify the root cause, let’s look at the relevant sections of the provided code that is responsible for checking internet connectivity.

[[See Video to Reveal this Text or Code Snippet]]

In this piece of code, _initializeApp() checks the internet status and updates the loading state. However, there’s a slight misunderstanding in the flow here that can lead to the flickering issue.

The Current Flow:

initState() gets called when the widget is inserted into the widget tree.

_initializeApp() checks for the internet connection asynchronously but sets loading to false immediately after checking.

The widget rebuilds, potentially showing NoInternet before being updated with the actual connectivity status.

The Solution

You can prevent the flickering effect by modifying the order in which the loading state is managed. Instead of setting isLoading to false immediately after checking internet connection, we can use the addPostFrameCallback to ensure that the UI builds only after the connectivity check is completed.

Updated Code Example

Below is the code that you should implement in your initState method:

[[See Video to Reveal this Text or Code Snippet]]

Key Changes Explained

WidgetsBinding.instance.addPostFrameCallback: This method schedules a callback to be run after the current frame is drawn. It allows you to safely await the internet connectivity check before updating the UI.

Setting the Loading State: The loading state is now set to false only after the internet check is complete, hence preventing the NoInternet widget from appearing prematurely.

Conclusion

By adjusting how you handle the loading state during your internet connectivity check, you can create a seamless experience for users interacting with your Flutter app. This small change can greatly enhance how your application feels and behaves, ultimately leading to a better user experience.

If you're new to Flutter, don't be discouraged! Each challenge you face is an opportunity to learn and improve your skills in mobile app development.

If you have any further questions or need assistance with your Flutter projects, feel free to reach out!