You can extract a dictionary value by key or an array value by index using type cast optional binding with subscript accessors or pattern matching with enumeration. To get an Array value from a JSON array type, conditionally cast it as (or an array with a more specific element type, like ). To get a Dictionary value from a JSON object type, conditionally cast it as. You can use optional binding and the as? type cast operator in an if or guard statement to extract a value of known type as a constant. Let data: Data // received from a network request, for example let json = try? JSONSerialization.jsonObject(with: data, options: )Īlthough valid JSON may contain only a single value, a response from a web application typically encodes an object or array as the top-level object. The JSONSerialization class method jsonObject(with:options:) returns a value of type Any and throws an error if the data couldn’t be parsed. This post describes a few approaches you can take when working with JSON in your apps. However, because you can’t be sure of the structure or values of JSON your app receives, it can be challenging to deserialize model objects correctly. You can use the Foundation framework’s JSONSerialization class to convert JSON into Swift data types like Dictionary, Array, String, Number, and Bool. If your app communicates with a web application, information returned from the server is often formatted as JSON. So, first things first: let’s create an object and convert it to a JSON data format. For the latest news, visit the Swift open source blog That’s enough for a basic usage of JSON in Swift, which will enable us to read JSON data (decode) and create a new object which can be converted back to JSON (encode) and send it, for instance, to a RESTFul API.
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