Understanding Why WillPopScope in Flutter Always Blocks Navigation Backwards

Discover the reason why Flutter's `WillPopScope` might always block your ability to navigate back and how to effectively resolve this issue with simple code fixes.
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Why Flutter's WillPopScope Always Blocks Going Back

If you are a Flutter developer working on iOS applications, you may have come across an unexpected behavior when using WillPopScope. Specifically, you might have noticed that even if you try to manipulate the back swipe gesture using the onWillPop callback, it always blocks your navigation, regardless of the returned value. In this post, we will explore why this happens and, most importantly, how to fix it.

Understanding WillPopScope

WillPopScope is a widget that allows you to control what happens when the user tries to navigate back in the app. This is crucial for defining user experience patterns, especially in complex applications where you might want to confirm actions or prevent unintended navigation.

Common Use-Cases for WillPopScope

Confirmation Dialogs: Prompting the user to confirm if they want to discard changes.

Navigation Control: Preventing back navigation in certain screens until certain criteria are met.

Cleanup: Performing necessary actions (like saving state) before leaving a screen.

The Issue with WillPopScope on iOS

Many developers have reported that regardless of the value returned in the onWillPop function, the swipe-back gesture is always disabled. This can lead to frustration, especially when testing if users can navigate back under certain conditions.

Here's a common example that illustrates the problem:

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

In this code, regardless of whether you have a hard-coded true or false, the app always blocks the back navigation.

The Solution: Correctly Implementing onWillPop

The key to solving this issue lies in how you handle the return value of the _isConfirmation method. If _isConfirmation is defined as an asynchronous function (which returns a Future), then you need to await its result.

Revised Code Implementation

You can fix the problem by ensuring that you await the result of _isConfirmation. Here's the updated code:

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

Why This Works

By using await, you ensure that the navigation decision is based on the actual outcome of your confirmation check. If _isConfirmation relies on asynchronous operations (like network calls, user input, or other futures), awaiting its response gives you the right boolean value to determine whether to allow or block navigation.

Conclusion

In conclusion, if you're facing issues with WillPopScope always blocking back navigation in your Flutter app, check if you're using asynchronous methods correctly. By adding await before your _isConfirmation() call, you can effectively control the back navigation behavior based on user confirmation or any necessary conditions in your app. Happy coding!