olbrichj

let timeout = after(seconds: 4)

race(when(fulfilled: fetch(url:url)).asVoid(), timeout).then {
    //…
}

olbrichj

func attempt<T>(maximumRetryCount: Int = 3, delayBeforeRetry: DispatchTimeInterval = .seconds(2), _ body: @escaping () -> Promise<T>) -> Promise<T> {
    var attempts = 0
    func attempt() -> Promise<T> {
        attempts += 1
        return body().recover { error -> Promise<T> in
            guard attempts < maximumRetryCount else { throw error }
            return after(delayBeforeRetry).then(on: nil, attempt)
        }
    }
    return attempt()

olbrichj

extension Foo {
    static func promise() -> Promise<FooResult> {
        return PromiseWithDelegate().promise
    }
}

class PromiseWithDelegate: FooDelegate {
    let (promise, seal) = Promise<FooResult>.pending()
    private let foo = Foo()

olbrichj

login().then { username in
    getTokens(for: username).map { ($0, username) }
}.then { tokens, username in
    //…
}

olbrichj

let p1 = promise1.then {
  ...
}

let p2 = promise2.then {
  ...
}

when(fulfilled: p1, p2).catch { error in
   ...

olbrichj

func foo() -> (Promise<Void>, cancel: () -> Void) {
    let task = Task(…)
    var cancelme = false

    let promise = Promise<Void> { seal in
        task.completion = { value in
            guard !cancelme else { reject(NSError.cancelledError) }
            seal.fulfill(value)
        }
        task.start()

olbrichj

class ViewController: UIViewController {
    private let (promise, seal) = Guarantee<...>.pending()

    func show(in: UIViewController) -> Promise<…> {
        in.show(self, sender: in)
        return promise
    }

    func done() {
        dismiss(animated: true)

olbrichj

et number = UInt32(Calendar.current.component(.weekday, from: Date()))
let msg = ["D", "(", "o", "o", "#", "(", "w", "k", "h", "#", "e", "(", "h", "v", "w", "!", "(", "#", "d", "q", "(", "g", "#", "n", "h", "h", ")", "s", "#", "r", "!", "q", "#", "h", "y", "d", "!", "o", "x", "d", "w", "(", "l", "q", "j"]
print(msg.filter{$0.unicodeScalars.map{$0.value}.reduce(0, +) > 64
    || $0.unicodeScalars.map{$0.value}.reduce(0, +) == 35}.map{
        Character(UnicodeScalar($0.unicodeScalars.map{$0.value}.reduce(0, +)
            - number)!)})

olbrichj

func rot3(msg: String, op: (UInt32, UInt32) -> UInt32) -> String {
    let numbers = msg.unicodeScalars.map{$0.value}
    return String(numbers.map{Character(UnicodeScalar(op($0, 3))!)})
}

olbrichj

func rotFinal(msg: String, key: String, op: (UInt32, UInt32) -> UInt32) -> String {
    return String(zip(msg.unicodeScalars.map{$0.value}, String(repeating: key, count: (msg.count / key.count) + 1)
            .unicodeScalars.map{$0.value})
                  .map{Character(UnicodeScalar(op($0.0, $0.1))!)})
}