iOS API Service [Swift|Alamofire]

In this short tutorial, you will learn how to write a thread safe API Service using below:

1. Alamofire
2. Codable

If you want to learn how to write a thread safe API Service in Android, Follow this

Android API Service [Kotlin|Retrofit|Coroutines]

Add dependencies

CocoaPods is a dependency manager for Cocoa projects. For usage and installation instructions, visit their website. To integrate Alamofire into your Xcode project using CocoaPods, specify it in your Podfile:

pod 'Alamofire', '~> 5.0'

Run pod install

Request and Response Classes

You can write Codable that easy to convert JSON.

• Model Class

struct User: Codable {
    var id:Int
    var name: String?
    var email: String?
}
//Your JSON will look like
{name: "Jhon", email: "jhon@example.com"}

• Request Class

struct UserRequest: Codable(
    var deviceId: String?
    var user: User
)
//Your JSON will look like
{deviceId: "XXXX" user: {name: "Jhon", email: "jhon@example.com"}}

• Response Class

struct BaseResponse: Codable {
    var message: String = ""
    var success: Boolean = false
}
struct UserResponse: Codable {
    var message: String = ""
    var success: Boolean = false
    var user: User? = null
    var token: String? = null
}
//Your JSON should look like
{token: "XXXX" user: {name: "Jhon", email: "jhon@example.com"}}

Service and Interface

• API Service

import Foundation
import Alamofire
enum APIService: APIConfiguration {
    case getUser()
    case createUser(request:UserRequest)
    case updateUser(request:UserRequest)
    // MARK: - HTTPMethod
    var method: HTTPMethod {
        switch self {
        case .getUser:
            return .get
        case .createUser:
            return .post
        case .updateUser:
            return .put
        }
   }
    // MARK: - Path
    var path: String {
        switch self {
        case .getUser:
            return "v1/profile"
        case .createUser:
            return "v1/profile"
        case .updateUser:
            return "v1/profile"
        }
    }
    // MARK: - Parameters
    var parameters: Parameters? {
        switch self {
        case .getUser:
            return []
        case .createUser(let request):
            return request.request
        case .updateUser(let request):
            return request.request
        }
    }
    // MARK: - URLRequestConvertible
    func asURLRequest() throws -> URLRequest {
        var url = try ServerParam.baseURL!.asURL()
        var urlRequest = URLRequest(url: url.appendingPathComponent(path))
    
        // HTTP Method
        urlRequest.httpMethod = method.rawValue
        // Common Headers
        urlRequest.setValue(ContentType.json.rawValue, forHTTPHeaderField: HTTPHeaderField.acceptType.rawValue)
        urlRequest.setValue(ContentType.json.rawValue, forHTTPHeaderField: HTTPHeaderField.contentType.rawValue)
        if let token  = UserDefaultManager.getStringValue(key: UserDefaultManager.keyAPIToken) {
            urlRequest.setValue(token, forHTTPHeaderField: HTTPHeaderField.authentication.rawValue)
        }
       // Parameters
       if let parameters = parameters {
           do {
               urlRequest.httpBody = try JSONSerialization.data(withJSONObject: parameters, options: [])
           } catch {
               throw AFError.parameterEncodingFailed(reason: .jsonEncodingFailed(error: error))
           }
       }
       return urlRequest
    }
}
extension Encodable {
    var dictionary: [String: Any]? {
        guard let data = try? JSONEncoder().encode(self) else { return nil }
        return (try? JSONSerialization.jsonObject(with: data, options: .allowFragments)).flatMap { $0 as? [String: Any] }
    }
    func toJSONData() -> Data? {
        return try? JSONEncoder().encode(self)
    }
}

• API Client

import Foundation
import Alamofire
class APIServiceClient {
    static func getUser(completion:@escaping (Result<UserResponse, Error>) -> Void) {
        AF.request(APIService.getUser())
.validate(statusCode: 200..<300)
.responseDecodable { (response: DataResponse<UserResponse>) in
            switch response.result {
                case .success:
                     completion(response.result)
                case .failure(let error):
                      APIErrorManager.handleError(statusCode: response.response?.statusCode ?? (error as? URLError)?.errorCode ?? 0)
            }
     }
     static func createUser(request: UserRequest, completion:@escaping (Result<UserResponse, Error>) -> Void) {
        AF.request(APIService.createUser(request:request))
.validate(statusCode: 200..<300)
.responseDecodable { (response: DataResponse<BaseResponse>) in
            switch response.result {
                case .success:
                     completion(response.result)
                case .failure(let error):
                      APIErrorManager.handleError(statusCode: response.response?.statusCode ?? (error as? URLError)?.errorCode ?? 0)
            }
     }
     static func updateUser(request: UserRequest, completion:@escaping (Result<UserResponse, Error>) -> Void) {
        AF.request(APIService.updateUser(request:request))
.validate(statusCode: 200..<300)
.responseDecodable { (response: DataResponse<BaseResponse>) in
            switch response.result {
                case .success:
                     completion(response.result)
                case .failure(let error):
                      APIErrorManager.handleError(statusCode: response.response?.statusCode ?? (error as? URLError)?.errorCode ?? 0)
            }
     }
}

• Error Handler

class APIErrorManager {
    static func handleError(statusCode: Int) {
         switch statusCode {
             case 401:
             //Invalid Session
             case -1009, -1005:
             //No internet
             case -1000, -1001, -1002, -1003:
             //Can't Connect to server
             default:
             //Log Error
         }
    }
}

In your ViewController

APIServiceClient.getUser() { result in
     switch result {
          case .success:
          //200
          case .failure:
          //Error
     }
}

From this post, we’ve learned how to write a thread safe API Service in iOS.

If you want to learn how to thread safe API Service Android, Follow this

Android API Service [Kotlin|Retrofit|Coroutines]

Thank you for reading.