cipolleschi

// Transform the presentation of a Modal VC into a promise.
// This pattern is useful when the modal has to pass some information back to the presenter
func promisifyModal() -> Promise<String> {
  return Promise<String>(in: .main) { resolve, _, _ in
    let vc = AnimalVC(store: self.store, connected: true, resolve: resolve)
    vc.modalPresentationStyle = .overFullScreen
    self.present(vc, animated: true, completion: nil)
  }
}

cipolleschi

// Data structure to hold the title of the UIAlertAction and the value that will resolve the promise
struct AlertCommand<T> {
  let title: String
  let returnValue: T
}

// Promisified implementation of the userTapDialog function
func userTapDialog() {
  _ = presentAlertVC(
    title: "Question!",

cipolleschi

func userTapDialog {

  // Create the alert
  let alertControl = UIAlertController(
        title: "Question!",
        message: "What's your favourite color?",
        preferredStyle: .alert
      )
  
  // add the red action

cipolleschi

// Promisification of asynchronous code:
func downloadUser() -> Promise<User> {
  return Promise<User> { 
    resolve, reject, cancellation in 
    self.downloadUser() { 
      user in
      resolve(user)
    }
  }
}

cipolleschi

let user = self.downloadUser()
let movies = self.downloadFavouriteMovies(for: user)
let ratings = self.downloadRatings(for: movies) 
let friends = self.downloadFriends(for: users)
let friendsMovies = self.downloadMovies(for: friends)
self.presentProfile(for: user, movies: movies, ratings: ratings, friends: friends, movies: movies)

cipolleschi

func prepareUserProfile() {
  self.downloadUser() { user in
    downloadUserMoviesAndFriendDataToPresentProfile(user: user)
  }
}

func downloadUserMoviesAndFriendDataToPresentProfile(user: User) {
  self.downloadFavouriteMovies(for: user) { movies in
    downloadRatingsAndFriendsDataThenPresentProfile(user: user, movies: movies)
  }

cipolleschi

self.downloadUser() { user in
  self.downloadFavouriteMovies(for: user) { movies in
    self.downloadRatings(for: movies) { ratings in
      self.downloadFriends(for: users) { friends in
        self.downloadMovies(for: friends] { friendMovies in
          self.presentProfile(
            for: user, 
            movies: movies, 
            ratings: ratings, 
            friends: friends,

cipolleschi

let operationQueue = OperationQueue()
operationQueue.addOperation { 
  // asynchronous task that will be executed somewhen in the future
}

cipolleschi

/// Protocol that defines the entities in our database.
/// They must have an identifier that is used to retrieve them.
protocol Entity {
  /// The identifier of the resource
  var id: String { get }
}

extension Entity {
  /// Helper to retrieve the table name from the Type of the entity.
  static var tableName: String { return String(reflecting: Self.self) }

cipolleschi

/// Protocol that defines the entities in our database.
/// They must have an identifier that is used to retrieve them.
protocol Entity {
  /// The identifier of the resource
  var id: String { get }
}

extension Entity {
  /// Helper to retrieve the table name from the Type of the entity.
  static var tableName: String { return String(reflecting: Self.self) }