Reversed UIViewPropertyAnimator for interactive navigation controller transition

Question

jayson OP

Created Oct ’18

Replies 1

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Views 2k

Participants 1

I'm trying to use a

UIViewPropertyAnimator

to drive a custom navigation controller transition. In my implementation, I set up the animation for the push transition, and then set

isReversed = true

on the animator if we actually need a pop transition.

This works fine for non-interactive transitions, and it mostly works for an interactive transition, but when I stop the interactive gesture and call

finish()

or

cancel()

on the interaction controller, it animates to the

.end

or

.start

position of the animation respectively, ignoring the

isReversed

property.

Is there a way to set this up such that when the property animator is reversed it finishes in the reverse direction?

I also have a sample project here that demonstrates the issue: https://github.com/jayrhynas/InteractiveTransitionTest

The relevant code is in DetailTransitionController.swift

Answered by jayson in 339682022

After submitting a DTS request and discussing with an Apple engineer, we came to the conclusion that this is not possible as is. His recommendation was to manually reverse the logic, either creating 2 separate animators for pushing and popping, or changing the code in the animation blocks based on the direction.

One workaround that techincally works in my case was to set up the animation for popping, and set

isReversed = true

when pushing. Since my app doesn't have an interactive push, this avoids the issue, however it requires reasoning about all your transitions in reverse.

Boost

Answer 1

jayson OP

Nov ’18

Accepted Answer

After submitting a DTS request and discussing with an Apple engineer, we came to the conclusion that this is not possible as is. His recommendation was to manually reverse the logic, either creating 2 separate animators for pushing and popping, or changing the code in the animation blocks based on the direction.

One workaround that techincally works in my case was to set up the animation for popping, and set

isReversed = true

when pushing. Since my app doesn't have an interactive push, this avoids the issue, however it requires reasoning about all your transitions in reverse.

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