![]() ![]() We can create this mapping by defining a custom CodingKeys enum: Taking the previous JSON example, it could be that we would like to name url as htmlLink in our JSON model. It’s quite common that you like to define different property names when mapping the JSON. JSON parsing isn’t always as easy as copying over the same keys into a struct. Print(unt) // Prints: 3 Mapping JSON keys to custom property names 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. Multi launches into early access today, so be the first to try it out! The basics of JSON decoding You can point, draw, or even take control of teammates’ apps. Xcode and any other macOS app instantly becomes multiplayer. If let dictionary = jsonString.Make Xcode Multiplayer with Multi Multi makes collaborating with teammates effortless. Here is an example code snippet − let jsonString = "" In Swift, you can convert a JSON string to a dictionary using the JSONSerialization class. The serialization and deserialization procedures are handled by the JSONSerialization class. Using the same class, you can also turn a dictionary or an array into a JSON object. To create a Swift dictionary or array, this class needs a string or data object. The Foundation framework for iOS and macOS includes a JSONSerialization class by default. Also, you can send image data in JSON string format. This converted string provides safety while sending in a request. This converted string can be used for networking requests or to store in the database. What is JSON String?Ī JSON string is a string that is converted to a different format such as base64 or URL encoding. In this article, you will see some examples of how to convert a JSON string into a dictionary. For example, you are receiving a JSON string from the database, in order to use it in the application, you might need to convert it into a real object type. Swift provides a class called JSONSerialization to convert a JSON string to dictionary format.
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