feat: Swap the native module used when in Expo managed workflow (#368)

* Add a .expo.js file to use the built-in react-native RCTAsyncStorage until RNC module ships with it

.github/CODEOWNERS

@@ -0,0 +1,2 @@
+# Expo managed workflow supported native backend
+/src/RCTAsyncStorage.expo.js @brentvatne

src/AsyncStorage.native.js

@@ -11,12 +11,7 @@
 
 'use strict';
 
-const {NativeModules} = require('react-native');
-
-const RCTAsyncStorage =
-  NativeModules.PlatformLocalStorage || // Support for external modules, like react-native-windows
-  NativeModules.RNC_AsyncSQLiteDBStorage ||
-  NativeModules.RNCAsyncStorage;
+import RCTAsyncStorage from './RCTAsyncStorage';
 
 if (!RCTAsyncStorage) {
   throw new Error(`[@RNC/AsyncStorage]: NativeModule: AsyncStorage is null.

src/RCTAsyncStorage.expo.js

@@ -0,0 +1,13 @@
+/**
+ * Expo managed apps don't include the @react-native-community/async-storage
+ * native modules yet, but the API interface is the same, so we can use the version
+ * exported from React Native still.
+ *
+ * If in future releases (eg: @react-native-community/async-storage >= 2.0.0) this
+ * will likely not be valid anymore, and the package will need to be included in the Expo SDK
+ * to continue to work.
+ */
+const {NativeModules} = require('react-native');
+const RCTAsyncStorage = NativeModules.AsyncSQLiteDBStorage || NativeModules.AsyncLocalStorage;
+
+export default RCTAsyncStorage;

src/RCTAsyncStorage.js

@@ -0,0 +1,8 @@
+const {NativeModules} = require('react-native');
+
+const RCTAsyncStorage =
+  NativeModules.PlatformLocalStorage || // Support for external modules, like react-native-windows
+  NativeModules.RNC_AsyncSQLiteDBStorage ||
+  NativeModules.RNCAsyncStorage;
+
+export default RCTAsyncStorage;