Let blogPosts: = try! JSONDecoder().decode(.self, from: jsonData) We can parse this list of blog posts by defining the decodable type as. "title": "Thread Sanitizer explained: Data Races in Swift", "title": "EXC_BAD_ACCESS crash error: Understanding and solving it", / Define a key as optional if it can be returned as `nil` or if it does not always exist in the JSON.ĭecoding a JSON array in Swift is almost just as easy as decoding a single JSON object. In this case, you can define a Swift property as optional and the JSONDecoder will take care of the rest.
It could be that you’re not sure whether a JSON key is returned or whether a value will be set. If it wouldn’t work like this, you could easily break old versions.
This is great, as it could be that you’re adding new keys after you’ve already released a version of your app. This means that the following struct would’ve worked as well: It’s good to know that you’re not required to define each property that comes with your JSON. It’s not required to define each property Luckily enough, Swift is capable enough to handle those as well. Print(blogPost.title) // Prints: "Optionals in Swift explained: 5 things you should know"Īlthough this might give the impression that JSON parsing is really easy, it all comes down to the edge cases. Let blogPost: BlogPost = try! JSONDecoder().decode(lf, from: jsonData) This means that you can also use your own custom defined Decodable types as a property.īy making use of a JSONDecoder we can make JSON parsing really simple: Every type that conforms to the Decodable protocol automatically converts.
All the properties match the names from our defined JSON example. We defined a Category enum that also conforms to the Decodable protocol. We can easily decode this by making use of the Decodable protocol: "title": "Optionals in Swift explained: 5 things you should know", Let’s take the following example of a SwiftLee blog post: It’s good to start with the basics to let you understand how JSON parsing in Swift works. It's available only until May 21st, so click to get it now! The basics of JSON decoding FREE iOS Architect Crash Course for a limited time! If you’re a mid/senior iOS developer looking to improve your skills and salary level, join this 100% free online crash course.
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