Скачать или смотреть How to Rethrow Errors in Swift for Asynchronous Functions

Learn how to effectively `rethrow errors` thrown by functions in Swift, ensuring error handling is efficient and seamless.
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Mastering Error Propagation in Swift: Rethrowing Errors Made Easy

When working with Swift, managing errors gracefully is crucial, especially when you're dealing with asynchronous functions. One common scenario developers encounter is needing to rethrow errors thrown by nested function calls. In this guide, we'll explore how you can effectively rethrow errors thrown by a generic function, ensuring a smooth error handling logic throughout your code.

The Problem at Hand

Consider a situation where you have a generic function called getResponse. This function can fail at multiple points, throwing specific errors based on the encountered issue. When calling this function from another function, you want to handle its errors appropriately without throwing a generic error. You aim to pass through the original error thrown by getResponse. Here’s a brief insight into the existing code structure:

The getResponse Function

This function handles the retrieval and decoding of data from a given URL and can throw several errors:

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The Calling Function

Your next function, getWorkoutList, attempts to call getResponse but encounters a challenge when managing errors:

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Currently, if getResponse throws an error, getWorkoutList throws its own error instead, which is not ideal.

The Solution: Rethrow the Error

To propagate the error from getResponse effectively, you can adjust your getWorkoutList function. Instead of using guard let with optional binding that catches the error, you would directly use try to await the result of getResponse. If an error is thrown, it will automatically be propagated upwards without the need for an additional error handling block.

Proposed Code Change

Here’s how you can make the adjustment:

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Remove the guard let: By eliminating the guard let, we're allowing Swift's error handling to manage the thrown error.

Directly using try await: This ensures that if getResponse fails, the error will be thrown by getWorkoutList as desired.

Conclusion

By implementing this simple fix, you can ensure that your Swift functions handle errors more effectively without masking the original issues. Now, when getResponse encounters an error, it will be caught by the calling function (getWorkoutList), preserving the integrity of your error handling logic. This approach leads to cleaner, more maintainable code and enhances the overall robustness of your Swift applications.

Now you can take your error handling skills to the next level! Happy coding!