Ttykuu

I've been implementing MVVM in Swift. I've looked at several implementations, many of which violate some aspects of MVVM and wanted to have a go with my own version that contains a Web request service.

View:

class BreachView: UIView 
 var nameLabel = UILabel()
 public override init(frame: CGRect) 
 let labelframe = CGRect(x: 0, y: 50, width: frame.width, height: 20)
 nameLabel.frame = labelframe
 nameLabel.backgroundColor = .gray
 super.init(frame: frame)
 self.addSubview(nameLabel)
 backgroundColor = .red
 

 required init?(coder aDecoder: NSCoder) 
 fatalError("init(coder:) has not been implemented")
 

ViewController
class ViewController: UIViewController

var breachesViewModel: BreachViewModelType!
var breachView : BreachView?

// to be called during testing
init(viewModel: BreachViewModelType) 
 breachesViewModel = viewModel
 super.init(nibName: nil, bundle: nil)


// required when called from storyboard
required init?(coder aDecoder: NSCoder) 
 breachesViewModel = BreachViewModel()
 super.init(coder: aDecoder)


override func viewDidLoad() 
 super.viewDidLoad() 
 breachesViewModel.fetchData [weak self] breaches in
 guard let self = self else return
 DispatchQueue.main.async 
 self.updateUI()
 
 


func updateUI() 
 breachView = BreachView(frame: view.frame)
 breachesViewModel.configure(breachView!, number: 3)
 view.addSubview(breachView!)

Protocol for dependency injection:

protocol BreachViewModelType 
 func fetchData(completion: @escaping ([BreachModel]) -> Void)
 func configure (_ view: BreachView, number index: Int)

ViewModel
class BreachViewModel : BreachViewModelType
var breaches = BreachModel

init() 
 // add init for ClosureHTTPManager here, to allow it to be teestable in the future


func fetchData(completion: @escaping ([BreachModel]) -> Void) 
 ClosureHTTPManager.shared.get(urlString: baseUrl + breachesExtensionURL, completionBlock: [weak self] result in
 guard let self = self else return
 switch result 
 case .failure(let error):
 print ("failure", error)
 case .success(let dta) :
 let decoder = JSONDecoder()
 do
 
 self.breaches = try decoder.decode([BreachModel].self, from: dta)
 completion(try decoder.decode([BreachModel].self, from: dta))
 catch 
 // deal with error from JSON decoding!
 
 
 )


func numberItemsToDisplay() -> Int 
 return breaches.count


func configure (_ view: BreachView, number index: Int) 
 // set the name and data in the view
 view.nameLabel.text = breaches[index].name

and HTTP manager

 class ClosureHTTPManager 
 static let shared: ClosureHTTPManager = ClosureHTTPManager()

 enum HTTPError: Error 


 case invalidURL
 case invalidResponse(Data?, URLResponse?)
 

 public func get(urlString: String, completionBlock: @escaping (Result<Data, Error>) -> Void) 
 guard let url = URL(string: urlString) else 
 completionBlock(.failure(HTTPError.invalidURL))
 return
 

 let task = URLSession.shared.dataTask(with: url) data, response, error in
 guard error == nil else 
 completionBlock(.failure(error!))
 return
 

 guard
 let responseData = data,
 let httpResponse = response as? HTTPURLResponse,
 200 ..< 300 ~= httpResponse.statusCode else 
 completionBlock(.failure(HTTPError.invalidResponse(data, response)))
 return
 

 completionBlock(.success(responseData))
 
 task.resume()
 
 

Calling the API from

let baseUrl : String = "https://haveibeenpwned.com/api/v2"
let breachesExtensionURL : String = "/breaches"

Any comments on whether the implementation conforms to MVVM or not, typos, changes etc. are appreciated.

Git link: https://github.com/stevencurtis/MVVMWithNetworkService