Linking.getInitialURL() for android

Hi, On Android Linking.getInitialURL() has a problem and not return anything. More precisely, none of the following logs are executed.

  Linking.getInitialURL().then((url) => {
      console.log('Initial url is: ' + url);
  }).catch(err => console.error('An error occurred', err));

but when i change https://github.com/facebook/react-native/blob/master/Libraries/Linking/Linking.js#L86-L92 to:

  getInitialURL(): Promise<?string> {
    return NativeLinking.getInitialURL();
  }

the problem was fixed.

React Native version:

System:
    OS: Linux 4.18 Ubuntu 18.04.2 LTS (Bionic Beaver)
    CPU: (8) x64 Intel(R) Core(TM) i7-6700HQ CPU @ 2.60GHz
    Memory: 582.26 MB / 15.50 GB
    Shell: 4.4.20 - /bin/bash
  Binaries:
    Node: 10.16.0 - /usr/bin/node
    Yarn: 1.17.3 - /usr/bin/yarn
    npm: 6.9.0 - /usr/bin/npm
    Watchman: 4.9.0 - /usr/local/bin/watchman
  SDKs:
    Android SDK:
      API Levels: 28
      Build Tools: 28.0.3, 29.0.0, 29.0.1
      System Images: android-28 | Intel x86 Atom, android-28 | Intel x86 Atom_64, android-28 | Google APIs Intel x86 Atom, android-28 | Google APIs Intel x86 Atom_64, android-28 | Google Play Intel x86 Atom, android-28 | Google Play Intel x86 Atom_64, android-29 | Google APIs Intel x86 Atom
      Android NDK: 20.0.5594570
  npmPackages:
    react: 16.8.6 => 16.8.6 
    react-native: 0.60.3 => 0.60.3 
  npmGlobalPackages:
    react-native-cli: 2.0.1

[xanderdeseyn]

Any progress on this? Seems mind boggling to me that deeplinking is just completely broken in RN for Android?

It’s not completely broken for me. It works for an already started app, but not for a newly started one.

Well I’d argue that is almost completely broken then. Deeplinking is usually used when the app is not open.

[jtbeach]

I think there are probably 2 different issues/bugs here:

1. The promise returned by Linking.getInitialURL() seems not to resolve for some people (see example of @crisvergara above)
2. The promise returned by Linking.getInitialURL() does resolve and either returns null or a default Expo URL starting with https://expo.io (only if using the managed Expo workflow)

I think it probably makes sense to separate these 2 issues or at least declare which of the 2 people are seeing. For me, I am seeing number 2 above.

I did some testing around this and have come to similar conclusions to @Stephen2:

• It does not seem related to a particular Android version, but actually depends on timing. That’s why it seems to happen on some phones rather than others I think. In addition to it only happening on certain phones, I found that you can get inconsistent results on the same phone if you repeat enough.
• It is resolved by moving back from React Native 0.61 to React Native 0.59. Unfortunately, for those using Expo, this means going back to the Expo 35 SDK, which Apple is no longer accepting submissions from due to usage of deprecated UIWebView (see https://github.com/expo/expo/issues/5497)
• It is not related to Expo and can be reproduced by a trivial example in latest React Native after running react-native init and making some changes to App.js and AndroidManifest.xml (to register intent to view certain URLs). I have pushed this sample app at https://github.com/stellaai/rndeeplink

Since the bug seems timing dependent and having put tracing debug statements throughout the native code, my hunch is that this relates to whether or not the React bridge is ready when the native code wants to set the initial URL by sending a message to the JS app via EventEmitter (if my reading of the code is correct and this is how it is set).

A workaround/hack (if using vanilla React Native or willing to eject from Expo managed workflow) might be to override the getLaunchOptions method in your own ReactActivityDelegate subclass to explicitly get the URI from the Intent and pass it through as a prop to the root React component rather than relying on Linking.getInitialUrl(). See https://medium.com/@anutoshdatta/pass-initial-properties-to-react-native-from-java-or-objective-c-code-12880ba6198e for some details on this.

I have put a video of these inconsistent results up here: https://github.com/stellaai/rndeeplink/blob/master/deeplinkbug.mp4 – note that pressing the the back button on Android destroys the activity, so this is showing a cold start every time.

Have also logged a bug in Expo prior to determining that this was a bug with RN upstream with some more logs, etc.: https://github.com/expo/expo/issues/8408