[iOS] Alamofire 网络请求 JSON 返回数据自动转换、映射至对象

AlamofireObjectMapper

An extension toAlamofire which automatically converts JSON response data into swift objects usingObjectMapper.

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 toObjectMapper'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 performed
• mapToObject : An object to perform the mapping on to
• completionHandler : 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 usingCarthage you can add a dependency on AlamofireObjectMapper by adding it to your Cartfile:

github "tristanhimmelman/AlamofireObjectMapper" ~> 3.0