Codable for API request - ios

Question

How would I make this same API request through codables?
In my app, this function is repeated in every view that makes API calls.
func getOrders() {
DispatchQueue.main.async {
let spinningHUD = MBProgressHUD.showAdded(to: self.view, animated: true)
spinningHUD.isUserInteractionEnabled = false
let returnAccessToken: String? = UserDefaults.standard.object(forKey: "accessToken") as? String
let access = returnAccessToken!
let headers = [
"postman-token": "dded3e97-77a5-5632-93b7-dec77d26ba99",
"Authorization": "JWT \(access)"
]
let request = NSMutableURLRequest(url: NSURL(string: "https://somelink.com")! as URL,
cachePolicy: .useProtocolCachePolicy,
timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers
let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
if (error != nil) {
print(error!)
} else {
if let dataNew = data, let responseString = String(data: dataNew, encoding: .utf8) {
print("----- Orders -----")
print(responseString)
print("----------")
let dict = self.convertToDictionary(text: responseString)
print(dict?["results"] as Any)
guard let results = dict?["results"] as? NSArray else { return }
self.responseArray = (results) as! [HomeVCDataSource.JSONDictionary]
DispatchQueue.main.async {
spinningHUD.hide(animated: true)
self.tableView.reloadData()
}
}
}
})
dataTask.resume()
}
}

Answer 1

I would suggest to do the following
Create Base Service as below
import UIKit
import Foundation
enum MethodType: String {
case get = "GET"
case post = "POST"
case put = "PUT"
case patch = "PATCH"
case delete = "DELETE"
}
class BaseService {
var session: URLSession!
// MARK: Rebuilt Methods
func FireGenericRequest<ResponseModel: Codable>(url: String, methodType: MethodType, headers: [String: String]?, completion: #escaping ((ResponseModel?) -> Void)) {
UIApplication.shared.isNetworkActivityIndicatorVisible = true
// Request Preparation
guard let serviceUrl = URL(string: url) else {
print("Error Building URL Object")
return
}
var request = URLRequest(url: serviceUrl)
request.httpMethod = methodType.rawValue
// Header Preparation
if let header = headers {
for (key, value) in header {
request.setValue(value, forHTTPHeaderField: key)
}
}
// Firing the request
session = URLSession(configuration: URLSessionConfiguration.default)
session.dataTask(with: request) { (data, response, error) in
DispatchQueue.main.async {
UIApplication.shared.isNetworkActivityIndicatorVisible = false
}
if let data = data {
do {
guard let object = try? JSONDecoder().decode(ResponseModel.self , from: data) else {
print("Error Decoding Response Model Object")
return
}
DispatchQueue.main.async {
completion(object)
}
}
}
}.resume()
}
private func buildGenericParameterFrom<RequestModel: Codable>(model: RequestModel?) -> [String : AnyObject]? {
var object: [String : AnyObject] = [String : AnyObject]()
do {
if let dataFromObject = try? JSONEncoder().encode(model) {
object = try JSONSerialization.jsonObject(with: dataFromObject, options: []) as! [String : AnyObject]
}
} catch (let error) {
print("\nError Encoding Parameter Model Object \n \(error.localizedDescription)\n")
}
return object
}
}
the above class you may reuse it in different scenarios adding request object to it and passing any class you would like as long as you are conforming to Coddle protocol
Create Model Conforming to Coddle protocol
class ExampleModel: Codable {
var commentId : String?
var content : String?
//if your JSON keys are different than your property name
enum CodingKeys: String, CodingKey {
case commentId = "CommentId"
case content = "Content"
}
}
Create Service to the specific model with the endpoint constants subclassing to BaseService as below
class ExampleModelService: BaseService<ExampleModel/* or [ExampleModel]*/> {
func GetExampleModelList(completion: ((ExampleModel?)/* or [ExampleModel]*/ -> Void)?) {
super.FireRequestWithURLSession(url: /* url here */, methodType: /* method type here */, headers: /* headers here */) { (responseModel) in
completion?(responseModel)
}
}
}
Usage
class MyLocationsController: UIViewController {
// MARK: Properties
// better to have in base class for the controller
var exampleModelService: ExampleModelService = ExampleModelService()
// MARK: Life Cycle Methods
override func viewDidLoad() {
super.viewDidLoad()
exampleModelService.GetExampleModelList(completion: { [weak self] (response) in
// model available here
})
}
}

Answer 2

Basically, you need to conform Codable protocol in your model classes, for this you need to implement 2 methods, one for code your model and another for decode your model from JSON
func encode(to encoder: Encoder) throws
required convenience init(from decoder: Decoder) throws
After that you will be able to use JSONDecoder class provided by apple to decode your JSON, and return an array (if were the case) or an object of your model class.
class ExampleModel: Codable {
var commentId : String?
var content : String?
//if your JSON keys are different than your property name
enum CodingKeys: String, CodingKey {
case commentId = "CommentId"
case content = "Content"
}
}
Then using JSONDecoder you can get your model array like this
do {
var arrayOfOrders : [ExampleModel] = try JSONDecoder().decode([ExampleModel].self, from: dataNew)
}
catch {
}

Answer 3

First of all, I can recommend you to use this application -quicktype- for turning json file to class or struct (codable) whatever you want. enter link description here.
After that you can create a generic function to get any kind of codable class and return that as a response.
func taskHandler<T:Codable>(type: T.Type, useCache: Bool, urlRequest: URLRequest, completion: #escaping (Result<T, Error>) -> Void) {
let task = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
if let error = error {
print("error : \(error)")
}
if let data = data {
do {
let dataDecoded = try JSONDecoder().decode(T.self, from: data)
completion(.success(dataDecoded))
// if says use cache, let's store response data to cache
if useCache {
if let response = response as? HTTPURLResponse {
self.storeDataToCache(urlResponse: response, urlRequest: urlRequest, data: data)
}
}
} catch let error {
completion(.failure(error))
}
} else {
completion(.failure(SomeError))
}
}
task.resume()
}