Open Native and Universal Native Modules With Jamie Birch

Birch describes NativeScript as an end-to-end framework that lets JavaScript call iOS and Android APIs directly. For example, JavaScript can create an iOS `NSString` with `NSString.alloc().init()`, without writing a native module. His longer-term aim is to make NativeScript usable within other frameworks, including React Native.

React Native, Flutter, and Capacitor each use different ways to connect JavaScript to native APIs, so their modules are not directly interchangeable. React Native’s classic modules use a JSON bridge, while Capacitor sends messages across a WebView boundary. Birch says this fragmentation makes smaller ecosystems repeat work and makes cross-framework reuse difficult.

Birch says Expo’s UniModules proposed a shared format, but Expo ended up doing most of the implementation work, and the effort was deprecated in 2021 in favor of Expo Modules. Open Native takes another approach: it aims to let NativeScript use existing React Native modules as they are, with package installation and autolinking handled by NativeScript. The episode describes this React Native-to-NativeScript path as the capability available at the time.

Open Native examines React Native’s module macros, registry, and bridge behavior, then uses build-time parsing to extract module names, methods, and signatures into JSON. Birch says the implementation used regular expressions because Objective-C AST approaches were slow. At runtime, NativeScript can load modules on demand and call methods directly, avoiding the classic JSON message round trip; the host cites performance figures in the repository that Birch recalls as possibly about 50 times faster.

Birch says adapting views is a later phase and was still under construction, with Open Native contributor Omar doing much of that work. View support would require an API-compatible equivalent to React Native’s `RCTView`, and React component libraries may not fit frameworks such as NativeScript Angular. Birch clarifies that Open Native did not yet let React Native consume Flutter modules; the demonstrated use was React Native modules from NativeScript.