Bouncer.swift

import Foundation

public typealias Action = ()->Void

/**

    Bounced action takes interval and action to return another action, which limits the rate at which provided action can be fired.
    It is like a bouncer at a discotheque. He will act on your questions only after you shut up for 'interval' of time.
    This technique is important if you have action wich should fire on update, however the updates coming in to frequently sometimes.
    
    Inspired by debounce function from underscore.js ( http://underscorejs.org )
*/
public func bouncedAction(interval : NSTimeInterval, action : Action) -> Action {
    let bouncer = Bouncer(interval: interval, action: action)
    return {
        bouncer.update()
    }
}


@objc internal class Bouncer {
    
    var timer : NSTimer?
    let action : Action
    let interval : NSTimeInterval
    
    private init(interval : NSTimeInterval, action : Action){
        self.action = action
        self.interval = interval
    }
    
    func update(){
        timer?.invalidate()
        
        timer = NSTimer.scheduledTimerWithTimeInterval(interval, target: self, selector: "execute", userInfo: nil, repeats: false)
    }
    
    func execute(){
        action()
    }
}