Every.swift

// Add <https://github.com/samhann/Every.swift/blob/master/NSDateComponentsExtensions.swift> here
import Foundation
import XCPlayground

struct Every {
    
    class Executor: NSObject {
        let closure: NSTimer -> Void
        var timer: NSTimer!
        init(closure: NSTimer -> Void) { self.closure = closure }
        func execute() { closure(timer) }
        
        deinit { print("done") }
    }
    
    init(_ duration: NSDateComponents, closure: NSTimer -> Void) {
        
        let executor = Executor(closure: closure)
        
        let timer = NSTimer.scheduledTimerWithTimeInterval(duration.durationInSeconds(), target: executor, selector: "execute", userInfo: nil, repeats: true)
        
        executor.timer = timer
    }
}

func main() {
    var counter = 0
    Every(1.seconds) { timer in
        
        counter += 1
        guard counter <= 5 else { timer.invalidate(); return }
        
        print("ran: \(counter)")
    }
}

main()

XCPlaygroundPage.currentPage.needsIndefiniteExecution = true

// prints:
//ran: 1
//ran: 2
//ran: 3
//ran: 4
//ran: 5
//done