Delegation example #1 for the Aya.io tutorial.

delegationExample01.swift

protocol ListensToEvents {
    func anEventHappened(code: Int)
}

class ClassicPrinter: ListensToEvents {
    func anEventHappened(code: Int) {
        print("CODE: \(code)")
    }
}

class FancyPrinter: ListensToEvents {
    func anEventHappened(code: Int) {
        print("\(NSDate()) - GENERATED CODE: \(code)")
    }
}

class EventsGenerator {
    var delegate: ListensToEvents?
    
    var codes = [Int]()
    
    func generateNewCode() {
        codes.append(Int(arc4random_uniform(1_000_000)))
        if let printer = delegate {
            printer.anEventHappened(codes.last!)
        } else {
            // No delegate, the code stays secret...
        }
    }
}

let generator = EventsGenerator()

generator.generateNewCode()

generator.delegate = ClassicPrinter()
generator.generateNewCode()

generator.delegate = FancyPrinter()
generator.generateNewCode()

generator.delegate = nil
generator.generateNewCode()

print(generator.codes)