Скачать или смотреть Resolving the Firebase Realtime Database Issue: How to Properly Fetch Data in Swift

This guide addresses a common issue faced by Swift developers when retrieving data from the Firebase Realtime Database. Learn how to ensure your data loads correctly in your SwiftUI views!
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This video is based on the question https://stackoverflow.com/q/70592805/ asked by the user 'Ardian Nuhiji' ( https://stackoverflow.com/u/16936153/ ) and on the answer https://stackoverflow.com/a/70593111/ provided by the user 'Sreekuttan' ( https://stackoverflow.com/u/11662833/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving the Firebase Realtime Database Issue: How to Properly Fetch Data in Swift

As a beginner in Swift, you may encounter challenges while working with asynchronous data fetching. One common issue is when data retrieved from the Firebase Realtime Database seems to be empty or not displayed correctly in your app. In this post, we'll dive into a specific problem and walk through the solution step-by-step.

The Problem

In the scenario we are discussing, the developer is attempting to display a list of "friends" fetched from Firebase. However, they observe that the data is being pulled after the function has already completed running, resulting in an empty view.

Here's a snippet from their getFriends function:

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

The challenge lies in the usage of the asynchronous method observeSingleEvent. This means that the completion(friends) call occurs before Firebase has had time to retrieve the data, leading to an empty array being returned.

The Solution

Update the getFriends Method

To resolve this issue, we need to call the completion(friends) in the closure of observeSingleEvent, after the data has been pulled and processed. Here’s the corrected version of the method:

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

Breakdown of Changes

Move the Completion Call: The completion(friends) line was moved inside the closure where data fetching occurs. This ensures it is called only after the data is fully retrieved and processed.

Clarify Print Statements: The timing of print statements should be accurate to help debug the code more effectively.

The Updated onAppear in your View

The view where getFriends is called does not require changes. Your onAppear will now work seamlessly:

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

Conclusion

By adjusting the placement of the completion call within the closure, we ensure that our Swift views receive the data only after it’s fully loaded from Firebase, allowing our apps to function correctly. Working with asynchronous calls can be tricky, especially when starting, but with these practices, you'll quickly improve your coding skills and troubleshoot effectively.

Whether you're a novice or an experienced developer, mastering the asynchronous nature of Firebase with Swift will greatly enhance your app's responsiveness and user experience.

Happy coding!