gistfile1.swift

import Cocoa
import AppKit

class MyCustomSwiftAnimator: NSObject, NSViewControllerPresentationAnimator {
    
    @objc func  animatePresentationOfViewController(viewController: NSViewController, fromViewController: NSViewController) {
        
        let bottomVC = fromViewController
        let topVC = viewController
        topVC.view.wantsLayer = true
        topVC.view.alphaValue = 0
        bottomVC.view.addSubview(topVC.view)
        
        var transition:CATransition = CATransition()
        transition.duration = 0.3
        transition.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
        transition.type = kCATransitionPush
        transition.subtype = kCATransitionFromRight
        transition.delegate = self
        
        NSAnimationContext.runAnimationGroup({ (transition) -> Void in
            
            transition.duration = 0.5
            let existingView = NSView.self
            let nextView = NSView.self
            topVC.view.animator().replaceSubview(existingView.self(), with: nextView.self())
            topVC.view.animator().alphaValue = 1
            bottomVC.view.animator().alphaValue = 0

        }, completionHandler: nil)
        
    }
    
    
    @objc func  animateDismissalOfViewController(viewController: NSViewController, fromViewController: NSViewController) {
        let bottomVC = fromViewController
        let topVC = viewController
        topVC.view.wantsLayer = true
        topVC.view.layerContentsRedrawPolicy = .OnSetNeedsDisplay
        
        NSAnimationContext.runAnimationGroup({ (transition) -> Void in
            
            transition.duration = 0.5
            let existingView = NSView.self
            let nextView = NSView.self
            topVC.view.animator().replaceSubview(existingView.self(), with: nextView.self())
            topVC.view.animator().alphaValue = 0
            bottomVC.view.animator().alphaValue = 1
            
            }, completionHandler: nil)
    }

}