AttatchButton.swift

//
//  AttatchButton.swift
//  Solution
//
//  Created by Cenny Davidsson on 2014-10-26.
//  Copyright (c) 2014 Cenny. All rights reserved.
//

import UIKit

class AttatchButton: UIButton {
    
    // MARK: Properties
    
    private var snapshootView: UIView!
    private var attatchmentBehavior: UIAttachmentBehavior!
    private var currentEvent: UIEvent!
    
    private var touchIsOutSide = false
    
    private lazy var animator: UIDynamicAnimator = { [unowned self] in
        return UIDynamicAnimator(referenceView: self.superview!)
        }()
    
    private lazy var gravity: UIGravityBehavior = { [unowned self] in
        var gravity = UIGravityBehavior()
        gravity.magnitude = 3
        gravity.action = { [unowned self] in
            if !self.snapshootView.frame.intersects(self.superview!.frame) {
                gravity.removeItem(self.snapshootView)
            }
        }
        self.animator.addBehavior(gravity)
        return gravity
        }()
    
    // MARK: Init
    
    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        addTargets()
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        addTargets()
    }
    
    private func addTargets() {
        [("touchDown", UIControlEvents.TouchDown),
            ("touchUpInside", UIControlEvents.TouchUpInside),
            ("touchDragOutside", UIControlEvents.TouchDragOutside),
            ("touchDragInside", UIControlEvents.TouchDragInside),
            ("touchUpOutside", UIControlEvents.TouchUpOutside)]
            .map {
                self.addTarget(self, action: $0.0, forControlEvents: $0.1)
        }
    }
    
    // MARK: UIControll
    
    override func sendAction(action: Selector, to target: AnyObject?,forEvent event: UIEvent?) {
        currentEvent = event
        super.sendAction(action, to: target, forEvent: event)
    }
    
    // MARK: Handle touch actions
    
    func touchDown() {
        // Create a copy view from orginal and hide orginial
        snapshootView = snapshotViewAfterScreenUpdates(true)
        snapshootView.frame = frame
        snapshootView.setShadowWithOffset(CGSize(), radius: 2, opacity: 0.5)
        
        superview!.addSubview(snapshootView)
        hidden = true
        
        // Apply dynamics
        let touch = currentEvent.touchesForView(self)!.anyObject()! as UITouch
        let touchInButton = touch.locationInView(self)
        let offset = UIOffset(horizontal: touchInButton.x - snapshootView.bounds.width/2, vertical: touchInButton.y - snapshootView.bounds.height/2)
        
        attatchmentBehavior = UIAttachmentBehavior(item: snapshootView, offsetFromCenter: offset, attachedToAnchor: touch.locationInView(superview!))
        
        animator.addBehavior(attatchmentBehavior)
        gravity.addItem(snapshootView)
    }
    
    func touchUpInside() {
        animator.removeBehavior(attatchmentBehavior)
    }
    
    func touchUpOutside() {
        snapshootView.removeFromSuperview()
    }
    
    func touchDragOutside() {
        if !touchIsOutSide {
            
            touchIsOutSide = true
            
            // Remove dangling state
            animator.removeBehavior(attatchmentBehavior)
            gravity.removeItem(snapshootView)
            
            // Return to orginial state
            UIView.animateWithDuration(0.3, animations: {
                self.snapshootView.transform = CGAffineTransformIdentity
                self.snapshootView.frame = self.frame
                }) { [unowned self] (_) in
                    self.snapshootView.hidden = true
                    self.hidden = false
            }
        }
    }
    
    func touchDragInside() {
        if touchIsOutSide {
            
            touchIsOutSide = false
            
            hidden = true
            snapshootView.hidden = false
            
            // Resume dangling state
            animator.addBehavior(attatchmentBehavior)
            gravity.addItem(snapshootView)
        }
    }
    
    // Animation
    
    func animateButtonBack() {
        gravity.removeItem(snapshootView)
        
        UIView.animateWithDuration(0.7, delay: 0, usingSpringWithDamping: 0.6, initialSpringVelocity: 0.6,
            options: .AllowUserInteraction | .AllowAnimatedContent | .BeginFromCurrentState,
            animations: { [unowned self] in
                
                self.snapshootView.transform = CGAffineTransformIdentity
                self.snapshootView.frame = self.frame
                
            }) { [unowned self] (_) in
                
                // Return to orginial state
                self.snapshootView.removeFromSuperview()
                self.hidden = false
        }
    }
}