Skip to content

Latest commit

 

History

History
250 lines (232 loc) · 11.1 KB

README.md

File metadata and controls

250 lines (232 loc) · 11.1 KB
Raw

@nativescript-community/expo-nativescript-adapter

An adapter to allow NativeScript to consume Expo Unimodules.

Installation

npm install --save @unimodules/core
ns plugin add @nativescript-community/expo-nativescript-adapter

Structure

expo-nativescript-adapter has the following peer dependencies:

Package

Native Module

Optional?

Purpose

iOS

Android

@unimodules/core

 UMCore org.unimodules.core Mandatory Implements the platform-agnostic API for consuming Expo Unimodules.

Status

See @unimodules/react-native-adapter to understand what modules I'm referring to here.

Feature

Support

Comments

iOS

Android

Constants

 ✅ 🚫 Blocked on the Android adapter. See "Android support" section below.

Methods

 ✅ 🚫 Blocked on the Android adapter. See "Android support" section below.

Module registry

 ✅ 🚫 Blocked on the Android adapter. See "Android support" section below.

Native modules proxy

 ✅ 🚫 Just need help filling in the Android implementation in NativeModulesProxy.ts.

Errors

 ✅ ✅ This is simply a JS API, so there wasn't much to it!

Events

 🚫 🚫 Need help understanding NativeScript's event model to port UMReactNativeEventEmitter.

Logging

 🚫 🚫 Need help understanding NativeScript's logging model to port UMReactLogHandler.

Fonts

 🚫 🚫 Looks surmountable. Seems we'd need to implement UMFontInterface.

UI

 🚫 🚫 We'll need to port UMViewManagerAdapter and UMViewManagerAdapterRegistry, which would involve implementing RCTViewManager. Not totally sure of feasibility, yet.

Bridge?

 🚫 🚫 I'm not sure whether we need to implement UMBridgeModule. 🤷‍♂️

Android support 🚧

I've spent weeks trying to implement Android support, but there are difficulties on both the Expo/React Native side and the NativeScript side, so I am stuck and need proper help on this front.

  • expo-permissions imports two interfaces from React Native, which is why I've had to introduce expo-nativescript-react-native-shim to provide those interfaces. I think that's working by now, but there might be a race condition involving order of installation. Not too sure.
  • Unimodules expect to find a package.json file in the parent directory of the Android app root (otherwise it will throw a GradleException); this means the platforms folder for NativeScript. As a workaround, I've written a hook in expo-nativescript-adapter to populate a dummy package.json in that location, but of course hooks are limited and very fragile to depend upon.
  • React Native plugins typically build from native source bundled in node_modules, rather than downloading JARs/AARs from an online repository. This is simply not a pattern used in NativeScript development, so there is no prior art to study as regards best practices. One particular issue is that Gradle projects must be declared up front, in the app's settings.gradle – you cannot simply declare them in each plugin's include.gradle. This is an enormous pain, as NativeScript provides no APIs to modify settings.gradle. So again, I've written some hooks to populate it, but inevitably they are fragile.
  • expo-permissions – and if I recall, various other Expo Unimodules – are written in Kotlin rather than Java. Although it seems possible to consume JARs/AARs that were generated from Kotlin sources, I have not found any prior art regarding creating NativeScript plugins by compiling directly from local Kotlin sources. I've tried various approaches, but even though I can get the Kotlin to compile to a JAR, I find it to contain no classes except BuildConfig.class inside.
  • Expo Unimodules need to register themselves into the Expo Adapter at the start of the app's lifecycle. Aside from the difficulty of implementing the necessary Package API for each plugin, NativeScript doesn't provide any lifecycle hooks for the plugins to auto-register themselves before the user-land code begins. Flutter, by contrast, does, through its registerWithRegistrar plugins API. React Native might admittedly be a bit more fiddly, but at least has a far more flexible build system for Android apps than NativeScript has. The only workaround I can think of for this would be to force the user to write some code into their NativeScript app's entrypoint (app.ts) which would call a register() function exported by each plugin. Yet again, this would introduce greater onboarding friction and chance of failure, and would be purely to fill in support for Android.
  • Generating TypeScript typings for the native sources of NativeScript plugins, while reasonably easy for iOS, is seriously laborious for Android.
  • Unlike on iOS (as far as I've seen), Unimodules for Android depend upon a concept of "Application Context". This is a significant extra complexity which entails hooking up NativeScript app lifecycle events to the Expo NativeScript Adapter. I've tried to stub it out for now, but I've no idea how that'll go.

So although I've made a lot of progress on all fronts, I've decided to wave the towel. If anyone can get expo-permissions to compile for Android (such that we could access its APIs via the NativeScript Android runtime), that would unblock me and I could have another try. But until then, I'm truly stuck and won't be spending any more time on Android support.

Usage

As a library user, you wouldn't be using these APIs directly. See apps/demo-react for examples of invoking the APIs; they're designed to map 1:1 to the Expo React Native APIs (as those are also written in TypeScript).

As a library developer... more details to come. Until I've written up some docs, just see how we use it in expo-permissions-nativescript-plugin and expo-contacts-nativescript-plugin.

License

MIT