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Discover how to efficiently call and return an array from a Swift class to a SwiftUI view by using completion handlers.
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This video is based on the question https://stackoverflow.com/q/64680763/ asked by the user 'Emrah Çağlar' ( https://stackoverflow.com/u/5227553/ ) and on the answer https://stackoverflow.com/a/64680841/ provided by the user 'Duncan C' ( https://stackoverflow.com/u/205185/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Properly Return an Array from a Swift Class to a SwiftUI View

If you're a Swift developer venturing into SwiftUI, you may encounter issues when trying to return data from a class to a SwiftUI view. A common problem arises when dealing with asynchronous network calls while trying to populate an array and return it to the view. In this guide, we'll explore why simply returning an array from a function may not work, and discuss an effective solution using completion handlers.

Understanding the Problem

In your code snippet, you attempted to create a function to fetch data from an API and return it as an array. Here's an overview of what you're doing:

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

You might have expected that calling GetSorular() would immediately give you the populated sorularArray. However, the underlying issue is that your NetworkManager's fetch() method is asynchronous. This means that:

The fetch() method starts a network request and returns immediately.

The completion closure you provide will only execute once the data fetch is complete.

As a result, when GetSorular() finishes executing, sorularArray has not been populated yet, leading to an empty result.

Embracing Completion Handlers

To fix this issue, we need to refactor the GetSorular() method to use a completion handler. This involves changing your function to accept a closure as a parameter, which will be executed once the data has been fetched.

Refactored Code

Here’s how your function might look using a completion handler:

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

Calling the Function

Now that the function is set up, here's how you would call it in your SwiftUI view:

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

Key Changes Explained

Completion Handler: Instead of trying to return the data directly, pass it through the completion handler. This ensures that the data is available only after the network call is complete.

Local Array: resultsArray is local to the getSorular method, promoting safer handling of data. This reduces the risk of unintended side effects.

Conclusion

By properly utilizing completion handlers in Swift, you can effectively manage asynchronous data fetching and ensure that your SwiftUI views have the data they need when they need it. This approach enhances readability and maintainability of your code, making it easier to handle complex data structures.

Next time you face a similar challenge, remember to look beyond direct returns and consider how asynchronous methods work in Swift!