PopUpTransition.swift

import Foundation
import UIKit


class PopUpTransition: NSObject, UIViewControllerAnimatedTransitioning {
    
    private var presenting:Bool = false
    
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
        return 0.4
    }
    
    
    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        
        let from = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey)!
        let to = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)!
        let container = transitionContext.containerView()!
        let bounds = UIScreen.mainScreen().bounds
        let offsetCenter = CGPoint(x: bounds.width / 2, y: bounds.height + 300)
        
        if presenting {
            
            to.view.center = offsetCenter
            container.addSubview(to.view)
            
            UIView.animateWithDuration(transitionDuration(transitionContext), delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 0.0, options: .CurveLinear, animations: {
                    from.view.alpha = 0.5
                    to.view.center = from.view.center
                
                }, completion: {
                    finished in
                    transitionContext.completeTransition(true)
                    
            })
            
            
        } else {
            
            container.addSubview(from.view)
            //container.addSubview(to.view)
            
            UIView.animateWithDuration(transitionDuration(transitionContext), delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 0.0, options: .CurveLinear, animations: {
                
                from.view.center = offsetCenter
                to.view.alpha = 1.0
                
                }, completion: {
                    finished in
                    transitionContext.completeTransition(true)
                    
            })
            
        }
    }
    
    func animationEnded(transitionCompleted: Bool) {
        print("Transition Completed")
    }
    
    
}


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