UIForceTouchGestureRecognizer.swift

//
//  ForceTouchGestureRecognizer.swift
//  Payment
//
//  Created by Wesley Cope on 5/5/16.
//  Copyright © 2016 Nudge, llc. All rights reserved.
//

import Foundation
import UIKit
import UIKit.UIGestureRecognizerSubclass
import AudioToolbox

class ForceTouchGestureRecognizer : UIGestureRecognizer {
    var threshold:CGFloat       = 1
    private var max:CGFloat     = 1
    private var force:CGFloat   = 0
    
    private var normalized:CGFloat {
        return force / max
    }
    
    override func touchesBegan(touches:Set<UITouch>, withEvent event:UIEvent) {
        super.touchesBegan(touches, withEvent: event)
        

        state = .Began
    }
    
    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent) {
        guard let touch = touches.first else { return }
        
        if touch.force != force {
            force   = touch.force
            max     = touch.maximumPossibleForce
            
            state = .Changed
        }
        
        if normalized >= threshold {
            state = .Ended
        }
        else if normalized > 0.75 {
            AudioServicesPlayAlertSound(kSystemSoundID_Vibrate)
        }
    }
    
    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent) {
        super.touchesEnded(touches, withEvent: event)
        
        state = .Changed
    }
}