![]() The only way is to implement the initializer and encoding function. The Swift compiler generates this for you from your properties' names for free, but if your property names don't exactly match the JSON data, or, as in this case, you don't want all of your properties to be parsed from JSON data, you must add your own. The CodingKeys enumeration must having a raw type of String and CodingKey (note the singular), in that order. This way is to define a enumeration of CodingKeys for your Codable type. There is a workaround for this, which we'll call ![]() But now it won't compile! Remember that every property of a Codable type that you want to convert to & from JSON must be a type that itself implements Codable, and DateFormatter does not. This is starting to look kind of ugly, but it should suit my purposes. One of them,, returns the following JSON when called with 3 (omitting some lines for clarity): I've recently been working with some REST APIs for looking up sunrise and sunset times for a given latitude and longitude. "Sunrise, Sunset" from The Fiddler on the Roof (1971) This article's focus is on supporting custom Date formats, and the journey I took from naïve implementation to full understanding. To make your data type Codable, you simply declare that it implements Codable, and ensure that all of its properties are themselves Codable or are one of the supported types:īy default, the JSONDecoder can parse Dates only in their raw form-a TimeInterval (= Double) of their milliseconds since the reference date: 12:00 a.m. When you declare a class, struct, or enum as Codable, the Swift compiler implicitly generates three things: init(from: Decoder), encode(to: Encoder), and a CodingKey enumeration, which maps JSON key values to the names of your Codable's properties. ![]() Xcode 9's Swift SDK introduced an elegant way to handle parsing, and that was with the Codable protocol. But for strongly-typed languages like Swift, this simplicity could lead to suboptimal parsing strategies. JSON's popularity lies in its simplicity: it supports only a handful of data types, like strings, numerics, Booleans, arrays, and dictionaries, and is generally easy for humans to read. If you've done any Web, mobile, or desktop programming in the past decade (and would you even be here if you hadn't?), you've used JSON-the lingua franca for serializing data across devices and platforms.
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