Struct Transformations

To map enums use the JMTransformerProtocol. Let's look at a dictionary for a business object, and see how we can map an enum to represent a struct for the coordinates:

Response Dictionary

{
	'business_uuid'  	: 9223123456754775807,
	'business_name'  	: 'NYC Restaurant',
	'business_longitude'  	: 40.7053319,
	'business_latitude'   	: -74.0129945,
}

Unlike the model objects, JSONModelKit does not autogenerate structs, due to the lack of inheritance. Structs would be un-customizable if it did, and would prevent the developer from using the many features Swift offers with structs. For the purposes of this example, let assume that we created a struct to represent the coordinates for our custom Business Object.

Struct Definition

struct Coordinate {
   var longitude: Double
   var latitude: Double
}

Once we have defined a Coordinate struct, let's create a mapper that parses out the values from the response and return the value of Coordinate type.

JSONModelKitCoordinateTransformer Implementation

let longitudeKey    = "longitude"
let latitudeKey     = "latitude"

public class JSONModelKitCoordinateTransformer : JMTransformerProtocol {

    public func transformValues(inputValues : Dictionary<String, Any>?) -> Any? {

        if let coordinateDictionary = inputValues as? Dictionary<String, Double> {
            if let unwrappedLongitude = coordinateDictionary[longitudeKey] {
                if let unwrappedLatitude = coordinateDictionary[latitudeKey] {
                    return Coordinate(longitude : unwrappedLongitude, latitude : unwrappedLatitude)
                }
            }
        }

        return nil
    }
}

Now that we have created a transformer, let's create some mapping for our business Object:

JSON: /Model/Mappings/Business.json	PLIST: /Mappings/Business.plist

After the creation of the mapping, perform a build (⌘-B). The changes should be reflected accordingly in the internal _Business.swift class.

import Foundation
import JSONModelKit

class _Business {
	var uuid : Double?
	var name : String?
	var coordinates : Coordinates?

 	required init() {...}

 	convenience init?(_ dictionary: Dictionary<String, Any>) {...}
}

After calling the fail-able initializer - or udpateWithDictionary method with a dictionary representation - JSONModelKit will use the custom transformer to map the struct accordingly.

Note: The the keys defined in the property mapping correspond to the keys in the dictionary of values passed to the public func transformValues(inputValues : Dictionary<String, Any>?) -> Any? method defined by the protocol.