[Feature Request] Transition only single NavigationLink calls

[Fesh-com]

Hi @davdroman,
I know you already answered this in Question 73 (different transitions per subview).
This lib doesn't support that.
Bummer.

Please, compare the situation to a book or article - you don't write the whole text in Comic Sans, but only a single line, to make it stand out.
The same applies to fancy transitions - you don't want them in your whole app, but only for this one special view.

I never would want to apply .navigationTransition() to the NavigationView (or -Stack) itself, but only to a single (or maybe a few)NavigationLink() and dismiss() calls.

If you support this, I'm sure way more developers would consider using this lib. I would...

The problem I need to solve is, that in standard SwiftUI (iOS 16ff) you can change the transition of a NavigationView push individually in the NavigationLink trigger (in my case disable the transition completely, just jump to the next view) like this:

    var transaction = Transaction()
    transaction.disablesAnimations = true
    withTransaction(transaction) {
        historyTapped = true          // ==> make NavigationLink go to history view
    }

but if you try the same for dismiss(), SwiftUI doesn't obey the transaction.disablesAnimationsand runs the usual slide back transition. I tried withTransaction(nil), or defined a transaction with a duration of 0.001 - didn't work, it always slides back. Asked Apple dts for help, got no answer... Guess they are too busy fixing iOS 26.

You do support a nothing transition which would solve my problem, but only if I can apply that to individual NavigationLink() and dismiss() calls instead of to the whole NavigationView.

Maybe a global variable would work for me to either use the standard iOS tableView / stack transition or nothing?

[davdroman]

There probably is a way to implement this, but I'm too busy at the moment to dive into it. PRs are always welcome if you want to take a crack at it.

[Fesh-com]

I already tried to understand the code.

		swizzle(
			UINavigationController.self,
			#selector(UINavigationController.popViewController),
			#selector(UINavigationController.popViewController_animateIfNeeded)
		)

This sets the dynamic pointer to the pop function (in Foundation) to your own function, which should do some magic and then call the original method.

However, your pop function

	@objc private func popViewController_animateIfNeeded(animated: Bool) -> UIViewController? {
		if let transitionDelegate = customDelegate {
			popViewController_animateIfNeeded(animated: transitionDelegate.transition.animation != nil)
		} else {
			popViewController_animateIfNeeded(animated: animated)
		}
	}

just calls itself - leading to an infinite loop.
Oh, wait, the swizzle executes

	method_exchangeImplementations(originalMethod, swizzledMethod)

thus the (recursive) call of popViewController_animateIfNeeded inside popViewController_animateIfNeeded does in fact call the original function UINavigationController.popViewController.
Got it.

Since all I want is popViewController(animated: false) - pushing without animation works already in SwiftUI by setting transaction.disablesAnimations - all I need to do is to swizzle this one call, for which I don't need to import your whole library.

Thanks for the fast reply though. And I will update the Demo app for iOS 15...