Make REST API call in Swift

Question

I'm trying to use Swift to make a GET call to a REST API, and have tried to follow numerous tutorials, but can't figure it out. Either because I cannot figure out how to translate all the Obj-C to Swift, or because half of the methods n' such are deprecated. Does anyone know how to make the call, and parse returned JSON data?

Answer 1

Swift 4

Create an app using Alamofire with Api Post method

Install pod file -pod 'Alamofire', '~> 4.0' for Swift 3 with Xcode 9

Create Webservices.swift class, import Alamofire

Design storyBoard ,Login View

insert following Code for the ViewControllerClass

import UIKit

class ViewController: UIViewController {

    @IBOutlet var usernameTextField: UITextField!

    @IBOutlet var passwordTextField: UITextField!
    var usertypeStr :String = "-----------"
    var loginDictionary : NSDictionary?
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func loginButtonClicked(_ sender: Any) {
        WebServices.userLogin(userName: usernameTextField.text!, password: passwordTextField.text!,userType: usertypeStr) {(result, message, status )in
            if status {
                let loginDetails = result as? WebServices
                self.loginDictionary = loginDetails?.loginData
                if self.loginDictionary?["status"] as? String == "error"
                {
                    self.alertMessage(alerttitle: "Login Error", (self.loginDictionary?["message"] as? String)!)
                } else if self.loginDictionary?["status"] as? String == "ok" {
                    self.alertMessage(alerttitle: "", "Success")

                }else {
                    self.alertMessage(alerttitle: "", (self.loginDictionary?["message"] as? String)!)
                }
            } else {
                self.alertMessage(alerttitle: "", "Sorry")
            }
        }
    }

    func alertMessage(alerttitle:String,_ message : String){
        let alertViewController = UIAlertController(title:alerttitle,  message:message, preferredStyle: .alert)
        alertViewController.addAction(UIAlertAction(title: "OK", style: .default, handler: nil))
        present(alertViewController, animated: true, completion: nil)
    }

}

Insert Following Code For WebserviceClass

import Foundation
import Alamofire
class WebServices: NSObject {
    enum WebServiceNames: String {
        case baseUrl = "https://---------------"
        case UserLogin = "------------"
    }

    // MARK: - Login Variables
    var loginData : NSDictionary?

    class func userLogin(userName: String,password : String,userType : String, completion : @escaping (_ response : AnyObject?, _ message: String?, _ success : Bool)-> ()) {
        let url = WebServiceNames.baseUrl.rawValue + WebServiceNames.UserLogin.rawValue
        let params = ["USER": userName,"PASS":password,"API_Key" : userType]
        WebServices.postWebService(urlString: url, params: params as [String : AnyObject]) { (response, message, status) in
            print(response ?? "Error")
            let result = WebServices()
            if let data = response as? NSDictionary {
                print(data)
                result.loginData = data
                completion(result, "Success", true)

            }else {
                completion("" as AnyObject?, "Failed", false)
            }
        }
    }
    //MARK :- Post
    class func postWebService(urlString: String, params: [String : AnyObject], completion : @escaping (_ response : AnyObject?, _ message: String?, _ success : Bool)-> Void) {
        alamofireFunction(urlString: urlString, method: .post, paramters: params) { (response, message, success) in
            if response != nil {
                completion(response as AnyObject?, "", true)
            }else{
                completion(nil, "", false)
            }
        }
    }

    class func alamofireFunction(urlString : String, method : Alamofire.HTTPMethod, paramters : [String : AnyObject], completion : @escaping (_ response : AnyObject?, _ message: String?, _ success : Bool)-> Void){

        if method == Alamofire.HTTPMethod.post {
            Alamofire.request(urlString, method: .post, parameters: paramters, encoding: URLEncoding.default, headers: nil).responseJSON { (response:DataResponse<Any>) in

                print(urlString)

                if response.result.isSuccess{
                    completion(response.result.value as AnyObject?, "", true)
                }else{
                    completion(nil, "", false)
                }
            }

        }else {
            Alamofire.request(urlString).responseJSON { (response) in

                if response.result.isSuccess{
                    completion(response.result.value as AnyObject?, "", true)
                }else{
                    completion(nil, "", false)
                }
            }
        }
    }



    //Mark:-Cancel
    class func cancelAllRequests()
    {
        Alamofire.SessionManager.default.session.getTasksWithCompletionHandler { dataTasks, uploadTasks, downloadTasks in
            dataTasks.forEach { $0.cancel() }
            uploadTasks.forEach { $0.cancel() }
            downloadTasks.forEach { $0.cancel() }
        }
    }
}

Answer 2

If you're working in Swift 3, the syntax changes. The example here worked for me and has a good explanation of the steps: https://grokswift.com/simple-rest-with-swift/

This is the code from that tutorial:

let todoEndpoint: String = "https://jsonplaceholder.typicode.com/todos/1"
guard let url = URL(string: todoEndpoint) else {
  print("Error: cannot create URL")
  return
}
let urlRequest = URLRequest(url: url)

let task = session.dataTask(with: urlRequest) {
  (data, response, error) in
  // check for any errors
  guard error == nil else {
    print("error calling GET on /todos/1")
    print(error!)
    return
  }
  // make sure we got data
  guard let responseData = data else {
    print("Error: did not receive data")
    return
  }
  // parse the result as JSON, since that's what the API provides
  do {
    guard let todo = try JSONSerialization.jsonObject(with: responseData, options: [])
      as? [String: Any] else {
      print("error trying to convert data to JSON")
      return
    }
    // now we have the todo
    // let's just print it to prove we can access it
    print("The todo is: " + todo.description)

    // the todo object is a dictionary
    // so we just access the title using the "title" key
    // so check for a title and print it if we have one
    guard let todoTitle = todo["title"] as? String else {
      print("Could not get todo title from JSON")
      return
    }
    print("The title is: " + todoTitle)
  } catch  {
    print("error trying to convert data to JSON")
    return
  }
}
task.resume()

Answer 3

You can do like this :

var url : String = "http://google.com?test=toto&test2=titi"
var request : NSMutableURLRequest = NSMutableURLRequest()
request.URL = NSURL(string: url)
request.HTTPMethod = "GET"

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue(), completionHandler:{ (response:NSURLResponse!, data: NSData!, error: NSError!) -> Void in
    var error: AutoreleasingUnsafeMutablePointer<NSError?> = nil
    let jsonResult: NSDictionary! = NSJSONSerialization.JSONObjectWithData(data, options:NSJSONReadingOptions.MutableContainers, error: error) as? NSDictionary

    if (jsonResult != nil) {
        // process jsonResult
    } else {
       // couldn't load JSON, look at error
    }


})

EDIT : For people have problem with this maybe your JSON stream is an array [] and not an object {} so you have to change jsonResult to NSArray instead of NSDictionary

Answer 4

edited for swift 2

let url = NSURL(string: "http://www.test.com")

    let task = NSURLSession.sharedSession().dataTaskWithURL(url!) {(data, response, error) in
        print(NSString(data: data!, encoding: NSUTF8StringEncoding))
    }

    task.resume()

Answer 5

Swift 4

let params = ["username":"john", "password":"123456"] as Dictionary<String, String>

var request = URLRequest(url: URL(string: "http://localhost:8080/api/1/login")!)
request.httpMethod = "POST"
request.httpBody = try? JSONSerialization.data(withJSONObject: params, options: [])
request.addValue("application/json", forHTTPHeaderField: "Content-Type")

let session = URLSession.shared
let task = session.dataTask(with: request, completionHandler: { data, response, error -> Void in
    print(response!)
    do {
        let json = try JSONSerialization.jsonObject(with: data!) as! Dictionary<String, AnyObject>
        print(json)
    } catch {
        print("error")
    }
})

task.resume()

Answer 6

swift 4

USE ALAMOFIRE in our App plz install pod file

pod 'Alamofire', '~> 4.0'

We can Use API for Json Data -https://swapi.co/api/people/

Then We can create A networking class for Our project- networkingService.swift

import Foundation
import Alamofire
typealias JSON = [String:Any]
class networkingService{
     static let shared = networkingService()
    private init() {}
    func getPeople(success successblock: @escaping (GetPeopleResponse) -> Void)
    {
    Alamofire.request("https://swapi.co/api/people/").responseJSON { response in
        guard let json = response.result.value as? JSON else {return}
       // print(json)
        do {
                let getPeopleResponse = try GetPeopleResponse(json: json)
                successblock(getPeopleResponse)
            }catch{}
    }
    }
    func getHomeWorld(homeWorldLink:String,completion: @escaping(String) ->Void){
        Alamofire.request(homeWorldLink).responseJSON {(response) in
            guard let json = response.result.value as? JSON,
            let name = json["name"] as? String
                else{return}
            completion(name)
        }
}
}

Then Create NetworkingError.swift class

import Foundation
enum networkingError : Error{
    case badNetworkigStuff

}

Then create Person.swift class

import Foundation
struct Person {
    private let homeWorldLink : String
    let birthyear : String
    let gender : String
    let haircolor : String
    let eyecolor : String
    let height : String
    let mass : String
    let name : String
    let skincolor : String
    init?(json : JSON) {
        guard let birthyear = json["birth_year"] as? String,
        let eyecolor = json["eye_color"] as? String,
        let gender = json["gender"] as? String,
        let haircolor = json["hair_color"] as? String,
        let height = json["height"] as? String,
        let homeWorldLink = json["homeworld"] as? String,
        let mass = json["mass"] as? String,
        let name = json["name"] as? String,
        let skincolor = json["skin_color"] as? String
        else { return nil }
        self.homeWorldLink = homeWorldLink
        self.birthyear = birthyear
        self.gender = gender
        self.haircolor = haircolor
        self.eyecolor = eyecolor
        self.height = height
        self.mass = mass
        self.name = name
        self.skincolor = skincolor
    }
    func homeWorld(_ completion: @escaping (String) -> Void)  {
        networkingService.shared.getHomeWorld(homeWorldLink: homeWorldLink){ (homeWorld) in
            completion(homeWorld)
        }
    }
}

Then create DetailVC.swift

import UIKit
class DetailVC: UIViewController {
    var person :Person!
    @IBOutlet var name: UILabel!
    @IBOutlet var birthyear: UILabel!
    @IBOutlet var homeworld: UILabel!
    @IBOutlet var eyeColor: UILabel!
    @IBOutlet var skinColor: UILabel!
    @IBOutlet var gender: UILabel!
    @IBOutlet var hairColor: UILabel!
    @IBOutlet var mass: UILabel!
    @IBOutlet var height: UILabel!
    override func viewDidLoad() {
        super.viewDidLoad()
       print(person)
        name.text = person.name
        birthyear.text = person.birthyear
        eyeColor.text = person.eyecolor
        gender.text = person.gender
        hairColor.text = person.haircolor
        mass.text = person.mass
        height.text = person.height
        skinColor.text = person.skincolor
        person.homeWorld{(homeWorld) in
            self.homeworld.text = homeWorld
        }
    }
}

Then Create GetPeopleResponse.swift class

import Foundation
struct GetPeopleResponse {
    let people : [Person]
    init(json :JSON) throws {
        guard let results = json["results"] as? [JSON] else { throw networkingError.badNetworkigStuff}
        let people = results.map{Person(json: $0)}.flatMap{ $0 }
        self.people = people
        }
}

Then Our View controller class

import UIKit

class ViewController: UIViewController {

    @IBOutlet var tableVieww: UITableView!
    var people = [Person]()


    @IBAction func getAction(_ sender: Any)
    {
    print("GET")
        networkingService.shared.getPeople{ response in
            self.people = response.people
           self.tableVieww.reloadData()
        }
    }
    override func prepare(for segue: UIStoryboardSegue, sender: Any?)
    {
        guard segue.identifier == "peopleToDetails",
        let detailVC = segue.destination as? DetailVC,
        let person = sender as AnyObject as? Person
        else {return}
        detailVC.person = person
        }
}
    extension ViewController:UITableViewDataSource{
        func numberOfSections(in tableView: UITableView) -> Int {
            return 1
        }
        func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
            return people.count
        }
        func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
         let cell = UITableViewCell()
            cell.textLabel?.text = people[indexPath.row].name

            return cell

        }
    }
extension ViewController:UITableViewDelegate{
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        performSegue(withIdentifier: "peopleToDetails", sender: people[indexPath.row])
    }
}

In our StoryBoard

plz Connect with our View with another one using segue with identifier -peopleToDetails

• Use UITableView In our First View

• Use UIButton For get the Data

• Use 9 Labels in our DetailVc