Resolving the SwiftUI ViewModel Initialization Issue: Fetching User Data Correctly

Learn how to fix the SwiftUI ViewModel initialization issue that prevents new user data from being reflected in your app. We'll go through a clear solution to ensure your UI updates as expected.
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Resolving the SwiftUI ViewModel Initialization Issue: Fetching User Data Correctly

SwiftUI has revolutionized the way developers build user interfaces on Apple platforms. However, while utilizing ViewModels to manage data, many developers run into some challenges, particularly when it comes to asynchronous data fetching.

In this post, we’ll specifically address the issue of the ViewModel taking initialized values instead of the fetched user data. Let’s dive into what’s happening and how to resolve the problem effectively.

The Problem Explained

You are working with a SwiftUI application that needs to fetch user data from a database (Firestore) based on the user's ID. You’ve correctly set up a ViewModel with a @ Published variable, but when you try to access the User's name, you see the default initialized value instead of the updated fetched value.

Key Observations:

You’ve implemented a method to fetch user data from Firestore.

Upon initialization of the ViewModel and calling getData(), it seems to fetch and print the correct user data but does not reflect in your SwiftUI View.

The output indicated that the print statements in init() of the ViewModel execute before the data fetching completion, resulting in the initial values being used.

The Solution

To ensure your ViewModel correctly updates the UI with the fetched data, you can utilize a completion handler in your data-fetching method. This allows you to wait for the async operation to complete before you try to use the data.

1. Modify the getData() Function

Change your getData() function to accept a completion closure that will be called once the data fetching is complete:

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

2. Update the init() Method

Next, you need to update the init() method in your ViewModel to use the revised getData() function and set the specificUser only after fetching the data successfully:

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

Conclusion

By modifying your data-fetching method to use a completion handler, you ensure that the user data is only processed and assigned after the fetch operation is complete. This approach allows your SwiftUI views to reflect the latest data properly, avoiding the issue of displaying initialized values.

With this fix, your ViewModel should work as intended, and updating user information from Firestore will seamlessly reflect in your application's UI. Happy coding with SwiftUI!