tylerlantern

class BHMenuTransitionManager: NSObject {
  
  var transitionAnimator : BHMenuTransitionAnimator!
  
  init(instance :  BHMenuTransitionManagerDelegate,fromViewController vc: UIViewController ) {
    super.init()
    transitionAnimator =  BHMenuTransitionAnimator(fromViewController: vc)
  }
  
}

tylerlantern

func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
  let containerView = transitionContext.containerView
  transitionContext.viewController(forKey: .from)
  let fromVc = transitionContext.viewController(forKey: .from)!
  let toVc = transitionContext.viewController(forKey: .to)!
  let isPresenting = self.fromViewController == fromVc ? true : false
  if  isPresenting{
    let targetWidth = fromVc.view.frame.width * 0.85
    toVc.view.frame = CGRect(x: targetWidth * -1, y: 0, width: targetWidth, height: fromVc.view.frame.height)
    containerView.addSubview(toVc.view)

tylerlantern

class BHMenuTransitionAnimator: NSObject , UIViewControllerAnimatedTransitioning  {
  
  var fromViewController : UIViewController!
  
  init(fromViewController vc  : UIViewController ) {
    super.init()
    self.fromViewController = vc
  }
  
  func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {