An extension to Alamofire which automatically converts JSON response data into swift objects using ObjectMapper.
#Usage
Given a URL which returns weather data in the following form:
{
"location": "Toronto, Canada",
"three_day_forecast": [
{
"conditions": "Partly cloudy",
"day" : "Monday",
"temperature": 20
},
{
"conditions": "Showers",
"day" : "Tuesday",
"temperature": 22
},
{
"conditions": "Sunny",
"day" : "Wednesday",
"temperature": 28
}
]
}
You can use the extension as the follows:
let URL = "https://raw.githubusercontent.com/tristanhimmelman/AlamofireObjectMapper/d8bb95982be8a11a2308e779bb9a9707ebe42ede/sample_json"
Alamofire.request(.GET, URL).responseObject { (response: Response<WeatherResponse, NSError>) in
let weatherResponse = response.result.value
print(weatherResponse?.location)
if let threeDayForecast = weatherResponse?.threeDayForecast {
for forecast in threeDayForecast {
print(forecast.day)
print(forecast.temperature)
}
}
}
The WeatherResponse
object in the completion handler is a custom object which you define. The only requirement is that the object must conform to ObjectMapper's Mappable
protocol. In the above example, the WeatherResponse
object looks like the following:
class WeatherResponse: Mappable {
var location: String?
var threeDayForecast: [Forecast]?
required init?(_ map: Map){
}
func mapping(map: Map) {
location <- map["location"]
threeDayForecast <- map["three_day_forecast"]
}
}
class Forecast: Mappable {
var day: String?
var temperature: Int?
var conditions: String?
required init?(_ map: Map){
}
func mapping(map: Map) {
day <- map["day"]
temperature <- map["temperature"]
conditions <- map["conditions"]
}
}
The extension uses Generics to allow you to create your own custom response objects. Below is the responseObject
function definition. Just replace T
in the completionHandler with your custom response object and the extension handles the rest:
public func responseObject<T: Mappable>(queue queue: dispatch_queue_t? = nil, keyPath: String? = nil, mapToObject object: T? = nil, completionHandler: Response<T, NSError> -> Void) -> Self
The responseObject
function has 3 optional parameters and a required completionHandler:
queue
: The queue on which the completion handler is dispatched.keyPath
: The key path of the JSON where object mapping should be performedmapToObject
: An object to perform the mapping on tocompletionHandler
: A closure to be executed once the request has finished and the data has been mapped by ObjectMapper.
###KeyPath
The keyPath
variable is used to drill down into a JSON response and only map the data found at that keyPath
. It supports nested values such as data.weather
to drill down several levels in a JSON response.
let URL = "https://raw.githubusercontent.com/tristanhimmelman/AlamofireObjectMapper/2ee8f34d21e8febfdefb2b3a403f18a43818d70a/sample_keypath_json"
let expectation = expectationWithDescription("\(URL)")
Alamofire.request(.GET, URL).responseObject(keyPath: "data") { (response: Response<WeatherResponse, NSError>) in
expectation.fulfill()
let weatherResponse = response.result.value
print(weatherResponse?.location)
if let threeDayForecast = weatherResponse?.threeDayForecast {
for forecast in threeDayForecast {
print(forecast.day)
print(forecast.temperature)
}
}
}
#Array Responses
If you have an endpoint that returns data in Array
form you can map it with the following function:
public func responseArray<T: Mappable>(queue queue: dispatch_queue_t? = nil, keyPath: String? = nil, completionHandler: Response<[T], NSError> -> Void) -> Self
For example, if your endpoint returns the following:
[
{
"conditions": "Partly cloudy",
"day" : "Monday",
"temperature": 20
},
{
"conditions": "Showers",
"day" : "Tuesday",
"temperature": 22
},
{
"conditions": "Sunny",
"day" : "Wednesday",
"temperature": 28
}
]
You can request and map it as follows:
let URL = "https://raw.githubusercontent.com/tristanhimmelman/AlamofireObjectMapper/f583be1121dbc5e9b0381b3017718a70c31054f7/sample_array_json"
Alamofire.request(.GET, URL).responseArray { (response: Response<[Forecast], NSError>) in
let forecastArray = response.result.value
if let forecastArray = forecastArray {
for forecast in forecastArray {
print(forecast.day)
print(forecast.temperature)
}
}
}
#Installation AlamofireObjectMapper can be added to your project using CocoaPods by adding the following line to your Podfile:
pod 'AlamofireObjectMapper', '~> 3.0'
If your using Carthage you can add a dependency on AlamofireObjectMapper by adding it to your Cartfile:
github "tristanhimmelman/AlamofireObjectMapper" ~> 3.0