Takahashi-meijin can push a button 16 times per 1 second.

UTContainer

final class UTContainer<T> {
    var value: T {
        didSet {
            if self.fired {
                self.fired = false
                self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: NSBlockOperation { [weak self] in
                    guard let strongSelf = self else {
                        return
                    }
                    strongSelf.fired = true
                    strongSelf.handler(strongSelf.value)
                }, selector: "main", userInfo: nil, repeats: false)
            } else {
                self.timer?.fireDate = NSDate(timeIntervalSinceNow: 1.0)
            }
        }
    }
    private var timer: NSTimer?
    private var handler: T -> ()
    private var fired = true
    init(_ value: T, handler: T -> ()) {
        self.value = value
        self.handler = handler
    }
}

var f = UTContainer(0) { i in
    print(i)
}
f.value = 1 // nop
NSRunLoop.currentRunLoop().runUntilDate(NSDate(timeIntervalSinceNow: 0.5))
f.value = 2 // nop
NSRunLoop.currentRunLoop().runUntilDate(NSDate(timeIntervalSinceNow: 0.5))
f.value = 3 // print
NSRunLoop.currentRunLoop().runUntilDate(NSDate(timeIntervalSinceNow: 1.2))
f.value = 4 // nop
NSRunLoop.currentRunLoop().runUntilDate(NSDate(timeIntervalSinceNow: 0.5))
f.value = 5 // print