We continue our look at frameworks that map JSON into model types today with Decodable by Johannes Lund. Decodable is another fantastic solution for this task. It takes advantage of Swift 2's new error handling functionality, and unlike ObjectMapper (covered in Bite #84), the properties on your models don't need to be optionals. Let's take a closer look:
To get things wired up we just need to implement the Decodableprotocol on our model types, like so:
Decodable also handles nested types and is quite flexible. For example, we aren't even forced to use Decodable on every type. Here we bypass Decodable a bit and instantiate a value for our rankproperty manually:
There are plenty (no really, plenty) of options when it comes to parsing JSON into model objects on iOS. We'll be taking a look at some of them from time to time over the coming weeks. First up is ObjectMapper by Hearst. Let's take a look how it works with a fictional set of types:
With ObjectMapper, we implement the Mappableprotocol on our types to support converting to and from JSON:
ObjectMapper can easily handle nested objects, here on our Spaceship model, we've got an optional User property for the captain of the ship.
It also supports subclasses and custom transforms when serializing/deserializing properties. One of the best things about ObjectMapper are the extensions available for other great iOS libraries like Alamofire and Realm (covered in Bite #49). Here's AlamofireObjectMapper in action: