CODEWITHSUNDEEP
iosswiftios8uinavigationcontrolleruiviewanimation
damianesteban
damianesteban

Reputation: 1611

iOS 8.4 + Swift - Custom Transitions from UINavigationController, how can I limit the behavior to only one transition in the Navigation Stack?

I've been dabbling with some very basic custom transitions recently and I'm starting to get the hang of it. Up until this point, however, I had only made Modal transitions.

I wrote the following code for a basic "Fade" transition from my "Master View" to my "Settings View" (both of which are part of the NavigationController Stack):

import UIKit
import QuartzCore

///Transition manager for transitioning between the loginVC and the content that follows.
class FadeTransition: NSObject, UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate, UINavigationControllerDelegate {

    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        let destinationVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey)
        let sourceView = transitionContext.viewForKey(UITransitionContextFromViewKey)
        let destinationView = transitionContext.viewForKey(UITransitionContextToViewKey)
        transitionContext.containerView().addSubview(destinationView!)

        UIView.animateWithDuration(self.transitionDuration(transitionContext), animations: { () -> Void in

            sourceView!.alpha = 0.0
            destinationView!.alpha = 1.0
            }) { (didComplete) -> Void in

                println("Fade Transition: \(didComplete)")
                transitionContext.completeTransition(didComplete)
        }
    }

    func transitionDuration(transitionContext: UIViewControllerContextTransitioning) -> NSTimeInterval {
        return 0.5
    }

    func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return self
    }

    func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return self
    }

    func navigationController(navigationController: UINavigationController, animationControllerForOperation operation: UINavigationControllerOperation, fromViewController fromVC: UIViewController, toViewController toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return self
    }


}

I was excited. I rejoiced. All appeared to be well until I then went to a different View Controller that also has a segue from the "Master View"...and it had the same transition. Of course this is to be expected, I just hadn't thought of it.

How can I limit this transition to only occur between two specific UIViewControllers?

Upvotes: 2

Views: 1598

Answers (1)

Stuart
Stuart

Reputation: 37053

You need to look at the UINavigationControllerDelegate method navigationController(_:animationControllerForOperation:fromViewController:toViewController). You have implemented it in your custom transition class above (I would suggest making a more general class your nav controller delegate instead, such as the view controller that contains it or the app delegate), but you return self indisciminately, indicating that every transition for that navigation controller should use your fade transition.

Instead, look at the from/toViewController parameters to decide whether you want to use a custom transition between those particular view controllers. If you want to use the default animated transition, just return nil.

From the UINavigationControllerDelegate Protocol Reference:

Return Value

The animator object responsible for managing the transition animations, or nil if you want to use the standard navigation controller transitions. The object you return must conform to the UIViewControllerAnimatorTransitioning protocol.

Upvotes: 1

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