Is this a bug report?

Yes

Have you read the Contributing Guidelines?

Yes

Environment

Expo project

Environment:
OS: Windows 10
Node: 6.12.3
Yarn: 1.3.2
npm: 3.10.10
Watchman: Not Found
Xcode: N/A
Android Studio: Version 2.3.0.0 AI-162.4069837

Packages: (wanted => installed)
react: 16.2.0 => 16.2.0
react-native: https://github.com/expo/react-native/archive/sdk-25.0.0.tar.gz => 0.52.0

Target Platform: iOS (11)

Steps to Reproduce

(Write your steps here:)

1. Swipe the top card either to the left or right appreciably
2. Past a certain swipe distance, the card will fly off the page.
3. This should invoke .start(() => this.onSwipeComplete(direction)), however, it does not. Passing in a regular function call works, but the function is called immediately, not on finishing of animation.timing.
   [e.g. .start( this.onSwipeComplete(direction)) ]

Expected Behavior

I expect a callback to be invoked in Animation.timing().start()

Actual Behavior

Nothing is invoked. I can also try console logging as a callback , and that does not work

Reproducible Demo

https://github.com/nthgol/swipe
Expo app

(Paste the link to an example project and exact instructions to reproduce the issue.)