Understanding How to Decode JSON in SwiftUI: Solve JSON Decode Failed Errors

Explore how to successfully decode JSON data into Swift data structures with a step-by-step guide. Learn to identify common errors and their solutions!
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Understanding How to Decode JSON in SwiftUI: Solve JSON Decode Failed Errors

The Problem: JSON Decode Error

The user provided a snippet of code where they were trying to decode JSON data into a Swift struct. However, they encountered the following error:

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

This error indicates that the decoder expected an array but found a dictionary instead. It suggests a mismatch between the structure of the JSON data and the Swift data model.

The JSON Structure

Here’s a look at the provided JSON data:

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

The JSON contains a single object that has an array called delivery_points and other dictionary fields. The structure of the Swift data model must align with this format.

The Solution: Revamping the Data Model

Based on the observed JSON structure, it is essential to adjust the Swift structs to match. Here’s a revised approach that can help avoid the JSON decode failed error:

Updated Swift Data Structures

1. Define DataFormatted and DeliveryPoint Structs:

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

2. Correct the Decoding Call:
Change the line in your loadData function to decode the data as DataFormatted rather than Array<DataFormatted>:

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

Example Code Implementation

Here's how the ContentView should look after the adjustments:

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

Conclusion

By aligning your Swift data model to the JSON structure, you can successfully decode JSON without errors. Remember to always verify that your struct properties match the JSON keys, and use an appropriate decode method for dictionaries and arrays. This approach will save you time and frustration when dealing with JSON in SwiftUI applications.

Happy coding! If you have further questions or improvements, feel free to ask!