swift - Custom segue transition animation

Question

I'm working on an app that utilizes the navigation controller. I have a certain view controller that has a left and right button in the navigation bar and each button segues to a different view controller. When I press the right button, I just call self.performSegue(withIdentifier: "ToDestination", sender: nil) and when I pop back I call _ = self.navigationController?.popViewController(animated: true).

My issue is when I press the left button. I can push and pop, but I want the transition to work opposite of the right button. Since I'm pressing the left button, I want the segue to transition from left to right, and when I pop, I want the segue to transition from right to left.

I can get the transitions to work the way I want by doing:

//push
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier: "SearchController") as! SearchController
let transition: CATransition = CATransition()
let timeFunc : CAMediaTimingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
transition.duration = 0.5
transition.timingFunction = timeFunc
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromLeft
self.navigationController!.view.layer.add(transition, forKey: kCATransition)
self.navigationController!.pushViewController(vc, animated: true)

//pop
let transition: CATransition = CATransition()
let timeFunc : CAMediaTimingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
transition.duration = 0.5
transition.timingFunction = timeFunc
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromRight
self.navigationController!.view.layer.add(transition, forKey: kCATransition)
_ = self.navigationController?.popViewController(animated: true)

This works, but there is a black flash when transitioning between view controllers. Is there a better way to get the default transition animation?

Answer 1

The best way to achieve that is to create custom push and pop animation by conforming UIViewControllerAnimatedTransitioning protocol:-

//CustomPushAnimation class

import UIKit

class CustomPushAnimation: NSObject, UIViewControllerAnimatedTransitioning {

    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.2
    }

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let containerVw = transitionContext.containerView
        let fromViewController = transitionContext.viewController(forKey: .from)
        let toViewController = transitionContext.viewController(forKey: .to)
        guard let fromVc = fromViewController, let toVc = toViewController else { return }
        let finalFrame = transitionContext.finalFrame(for: toVc)
        //Below line will start from left
        toVc.view.frame = finalFrame.offsetBy(dx: -finalFrame.size.width/2, dy: 0)
        containerVw.addSubview(toVc.view)
        UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
            toVc.view.frame = finalFrame
            fromVc.view.alpha = 0.5
        }, completion: {(finished) in
            transitionContext.completeTransition(finished)
            fromVc.view.alpha = 1.0
        })
    }
}



//CustomPopAnimation class
import UIKit

class CustomPopAnimation: NSObject, UIViewControllerAnimatedTransitioning {
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.2
    }

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
        let containerView = transitionContext.containerView
        let fromViewController = transitionContext.viewController(forKey: .from)
        let toViewController = transitionContext.viewController(forKey: .to)
        guard let fromVc = fromViewController,
            let toVc = toViewController,
            let snapshotView = fromVc.view.snapshotView(afterScreenUpdates: false)
            else { return }
        let finalFrame = transitionContext.finalFrame(for: fromVc)
        toVc.view.frame = finalFrame
        containerView.addSubview(toVc.view)
        containerView.sendSubview(toBack: toVc.view)
        snapshotView.frame = fromVc.view.frame
        containerView.addSubview(snapshotView)
        fromVc.view.removeFromSuperview()
        UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: {
            //Below line will start from right
            snapshotView.frame = finalFrame.offsetBy(dx: -finalFrame.size.width, dy: 0)
        }, completion: {(finished) in
            snapshotView.removeFromSuperview()
            transitionContext.completeTransition(finished)
        })
    }
}

And last you need to present the new View controller with setting animation flag to true otherwise it will not work

//Below code should be inside YourViewController
    let vc = UIStoryboard(name: "storyboardName", bundle: nil).instantiateViewController(withIdentifier: "ViewControllerIdentifier")            let navigationController = BaseNavigationController(rootViewController: vc)
    navigationController.transitioningDelegate = self
    present(navigationController, animated: true, completion: nil)

You also need to conform UIViewControllerTransitioningDelegate protocol in order to work animation

  extension YourViewController: UIViewControllerTransitioningDelegate {
    func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
            return customPushAnimation
        }

    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
            return customPopAnimation
        }
    }