onmyway133

private func setupAVSession() {
  captureSession.beginConfiguration()
  captureSession.sessionPreset = .high

  defer {
    captureSession.commitConfiguration()
  }

  // input
  guard

onmyway133

let signal = PullSignal<String> { completion in
  // There should be some long running operation here
  completion(Result.value(value: "test"))
}

signal.map { value in
  value.count
}.start { event in
  if case let .value(value) = event {
    print(value)

onmyway133

public struct PullSignal<T> {
  let operation: ((Result<T>) -> Void) -> Void

  public init(operation: @escaping ((Result<T>) -> Void) -> Void) {
    self.operation = operation
  }

  public func start(completion: (Result<T>) -> Void) {
    operation() { event in
      completion(event)

onmyway133

let signal = PushSignal<String>()

_ = signal.map { value in
  return value.count
}.subscribe { event in
  if case let .value(value) = event {
    print(value)
  } else {
    print("error")
  }

onmyway133

public final class PushSignal<T> {
  var event: Result<T>?
  var callbacks: [(Result<T>) -> Void] = []
  let lockQueue = DispatchQueue(label: "Serial Queue")

  func notify() {
    guard let event = event else {
      return
    }

onmyway133

enum Result<T> {
  case value(value: T)
  case failure(error: Error)

  // Sync
  public func map<U>(f: (T) -> U) -> Result<U> {
    switch self {
    case let .value(value):
      return .value(value: f(value))
    case let .failure(error):

onmyway133

class MyActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) {
        super.onCreate(savedInstanceState, persistentState)

        val model = ViewModelProviders.of(this).get(MyViewModel::class.java)
        model.getUsers().observe(this, { users ->
            // update UI
        })
    }
}

onmyway133

// Sync
func sum(a: Int, b: Int) -> Int {
    return a + b
}

// Async
func sum(a: Int, b: Int, completion: Int -> Void) {
    // Assumed it is a very long task to get the result
    let result = a + b

onmyway133

class ProfileViewController: BaseViewController<ProfileView> {
  let viewModel: ProfileViewModelType
  init(viewModel: ProfileViewModelType) {
    self.viewModel = viewModel
  }
  override func viewDidLoad() {
    super.viewDidLoad()
    // Input
    viewModel.input.fetch.onNext(())
    // Output

onmyway133

class ViewModel {
  class Input {
    let fetch = PublishSubject<()>()
  }
  class Output {
    let friends: Driver<[User]>
  }
  let apiClient: APIClient
  let input: Input
  let output: Output