How to Filter JSON Data Based on Enum Values in Swift

Learn how to exclude unwanted JSON data by filtering it according to an enum case in Swift. Get step-by-step guidance using Alamofire and Codable.
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Filtering JSON Data in Swift: Keep What Matters

Have you ever faced the challenge of parsing JSON data while needing to filter out unwanted values? This is a common scenario when working with APIs, especially if the data contains a wide range of options not relevant to your application. In this guide, we will explore how you can filter JSON data in Swift to only include certain values based on an enum case. We’ll walk through a practical example involving a struct implementation using the Codable protocol and the Alamofire library for network requests.

The Problem

Imagine you have a JSON response from an API that looks like this:

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

You want to decode this into a Swift struct called ServicesList and only keep the services that match the cases defined in your Service.Name enum. However, you'll run into an error if you try to decode a value that doesn't match any enum case:

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

The Solution

To solve this problem, we can customize the decoding process by introducing a failable initializer for our Service struct and implementing a custom initializer in the ServicesList struct. Let's break this down step by step.

Step 1: Create a Failable Initializer for Service

We start with the Service struct where we define a custom initializer that attempts to create an instance based on the provided serviceName and date. Here's how that looks:

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

Step 2: Override the Decoding Process in ServicesList

Next, we need to implement a custom initializer in the ServicesList struct that decodes each item from the JSON and checks if it can be initialized as a valid Service. Here is the implementation:

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

Step 3: Using Alamofire to Fetch and Decode

Lastly, combine everything together by setting up Alamofire to make your API call and decode the data into your ServicesList struct.

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

Conclusion

In summary, by enhancing the decoding process with custom initializers, you can efficiently filter JSON data based on enum case values in Swift. This not only allows you to eliminate unneeded values but also keeps your codebase clean and robust while adhering to the principles of type safety inherent in Swift. Happy coding!