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.

JMTransformerProtocol Implementation

let longitudeKey = "business_longitude"
let latitudeKey = "business_latitude"
public class CoordinateTransformer : JMTransformerProtocol {
public func transformValues(inputValues : Dictionary<String, Any>?) -> Any? {
if let coordinateDictionary = inputValues as? Dictionary<String, Double>,
let longitude = coordinateDictionary[longitudeKey], let latitude = coordinateDictionary[latitudeKey] {
return Coordinate(longitude : longitude, latitude : latitude)
}
}
}
return nil
}
}

Mapping

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

/Model/Mappings/Business.json | PLIST Equivalent

{
"uuid" : { ... },
"fullName" : {
"transformer" : "CoordinateTransformer",
"type" : "Coordinate",
"key" : [
"business_longitude",
"business_latitude"
]
}
}

Model

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.