view controller transition from origin view to another view controller.

TransformTransitioning.swift

//: Playground - noun: a place where people can play

import UIKit
import XCPlayground


extension UIView{
    
    var snapshot: UIImage{
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, 0);
        drawViewHierarchyInRect(bounds, afterScreenUpdates:true)
        let image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        return image
    }
}


class TransformTransitioning: NSObject, UIViewControllerAnimatedTransitioning {
    
    var originView: UIView?
    var snapShot: UIImage!
    var presenting = false
    
    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        
        // view contontroller
        guard let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey) else { return }
        guard let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey) else { return }
        
        // view
        guard let containerView = transitionContext.containerView() else { return }
        guard let fromView = transitionContext.viewForKey(UITransitionContextFromViewKey) else { return }
        guard let toView = transitionContext.viewForKey(UITransitionContextToViewKey) else { return }
        
        guard let originView = originView else { return }
        
        // frame
        let containerFrame = containerView.frame
        
        // take snapshot
        if presenting{
            snapShot = originView.snapshot
        }
        
        let imageView = UIImageView(image: snapShot)
        imageView.contentMode = .ScaleAspectFill
        imageView.clipsToBounds = true
        
        // calculate scale
        let scaleX = originView.frame.width / containerFrame.width
        let scaleY = originView.frame.height / containerFrame.height
        
        let toViewStartTransform: CGAffineTransform
        let toViewStartCenter: CGPoint
        
        if presenting{
            toViewStartTransform = CGAffineTransformMakeScale(scaleX, scaleY)
            toViewStartCenter = originView.center
        }else{
            toViewStartTransform = CGAffineTransformIdentity
            toViewStartCenter = containerView.center
        }
        
        imageView.alpha = 1.0
        imageView.frame = presenting ? originView.frame : containerView.frame
        
        containerView.addSubview(imageView)
        containerView.addSubview(toView)
        
        // set frame
        toView.frame = containerFrame
        fromView.frame = containerFrame
        
        if presenting{
            toView.transform = toViewStartTransform
            toView.center = toViewStartCenter
            
            containerView.bringSubviewToFront(imageView)
        }else{
            containerView.bringSubviewToFront(imageView)
            containerView.bringSubviewToFront(fromView)
        }
        
        let duration = transitionDuration(transitionContext)
        
        UIView.animateWithDuration(duration,
            animations: {
                if self.presenting{
                    
                    toView.transform = CGAffineTransformIdentity
                    toView.center = containerView.center
                    
                    imageView.frame = containerView.frame
                    imageView.alpha = 0.0
                    
                }else{
                    
                    fromView.transform = CGAffineTransformMakeScale(scaleX, scaleY)
                    fromView.center = originView.center
                    fromView.alpha = 0.0
                    
                    imageView.frame = originView.frame
                }
            },
            completion:{ finish in
                
                imageView.removeFromSuperview()
                
                let success = !transitionContext.transitionWasCancelled()
                if ((self.presenting && !success) || (!self.presenting && success)) {
                    toView.removeFromSuperview()
                }
                
                // reset transform
                fromView.transform = CGAffineTransformIdentity
                toView.transform = CGAffineTransformIdentity
                
                transitionContext.completeTransition(success)
        })
        
    }
    
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
        return 0.6
    }
    
}



class ViewController: UIViewController {
    
    let transformTransitioning = TransformTransitioning()
    
    let originView = UIView()
    
    override func viewDidLoad() {
        
        view.backgroundColor = UIColor.darkGrayColor()
        view.addSubview(originView)
        
        transformTransitioning.originView = originView
        transformTransitioning.presenting = true
        
        transitioningDelegate = self
    }
    
    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        
        originView.layer.cornerRadius = 10.0
        originView.backgroundColor = UIColor.whiteColor()
        originView.frame.size = CGSize(width: view.frame.width/2.0, height: view.frame.height/2.0)
        originView.center = view.center
        originView.frame.origin.x -= 50
    }
}

extension ViewController: UIViewControllerTransitioningDelegate{
    
    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        transformTransitioning.presenting = true
        return transformTransitioning
    }
    
    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        transformTransitioning.presenting = false
        return transformTransitioning
    }
    
}


let a = ViewController()
let b = UIViewController()

b.transitioningDelegate = a
b.view.backgroundColor = UIColor.yellowColor()

XCPlaygroundPage.currentPage.liveView = a

a.presentViewController(b, animated: true, completion: {
    a.dismissViewControllerAnimated( true, completion: nil)
})