feat: add JSBundle load for Expo and make it reusable

Author: hurali97

packages/react-native-brownfield/ios/ExpoHostRuntime.swift

@@ -9,6 +9,7 @@ internal import Expo
 final class ExpoHostRuntime {
   static let shared = ExpoHostRuntime()
 
+  private let jsBundleLoadObserver = JSBundleLoadObserver()
   private var delegate = ExpoHostRuntimeDelegate()
   private var reactNativeFactory: RCTReactNativeFactory?
   private var expoDelegate: ExpoAppDelegate?
@@ -35,6 +36,10 @@ final class ExpoHostRuntime {
     let appDelegate = ExpoAppDelegate()
     appDelegate.bindReactNativeFactory(factory)
     expoDelegate = appDelegate
+
+    if let onBundleLoaded {
+      jsBundleLoadObserver.observeOnce(onBundleLoaded: onBundleLoaded)
+    }
   }
 
   /**
@@ -91,19 +96,15 @@ final class ExpoHostRuntime {
     moduleName: String,
     initialProps: [AnyHashable: Any]?,
     launchOptions: [AnyHashable: Any]?
-  ) -> UIView {
+  ) -> UIView? {
     let bundleURL = delegate.bundleURL()
 
-    if let view = expoDelegate?.recreateRootView(
+    return expoDelegate?.recreateRootView(
       withBundleURL: bundleURL,
       moduleName: moduleName,
       initialProps: initialProps,
       launchOptions: launchOptions
-    ) {
-      return view
-    }
-
-    return UIView(frame: .zero)
+    )
   }
 }
 

packages/react-native-brownfield/ios/JSBundleLoadObserver.swift

@@ -0,0 +1,38 @@
+import Foundation
+internal import React
+
+final class JSBundleLoadObserver {
+  private var onBundleLoaded: (() -> Void)?
+  private var observerToken: NSObjectProtocol?
+
+  func observeOnce(onBundleLoaded: @escaping () -> Void) {
+    removeObserverIfNeeded()
+    self.onBundleLoaded = onBundleLoaded
+
+    observerToken = NotificationCenter.default.addObserver(
+      forName: NSNotification.Name("RCTInstanceDidLoadBundle"),
+      object: nil,
+      queue: nil
+    ) { [weak self] _ in
+      self?.notifyAndClear()
+    }
+  }
+
+  deinit {
+    removeObserverIfNeeded()
+  }
+
+  private func notifyAndClear() {
+    let callback = onBundleLoaded
+    onBundleLoaded = nil
+    removeObserverIfNeeded()
+    callback?()
+  }
+
+  private func removeObserverIfNeeded() {
+    if let observerToken {
+      NotificationCenter.default.removeObserver(observerToken)
+      self.observerToken = nil
+    }
+  }
+}

packages/react-native-brownfield/ios/ReactNativeBrownfield.swift

@@ -9,7 +9,7 @@ internal import Expo
 
   /**
    * Path to JavaScript root.
-   * Default value: "index"
+   * Default value: "index" for bare React Native, ".expo/.virtual-metro-entry" when built with Expo.
    */
   @objc public var entryFile: String = {
     #if canImport(Expo)
@@ -61,7 +61,7 @@ internal import Expo
    * Returns a URL to load a custom bundle, or nil to use default behavior.
    * Default value: nil
    */
-  @objc public var bundleURLOverride: (() -> URL?)? {
+  @objc public var bundleURLOverride: (() -> URL?)? = nil {
     didSet {
       #if canImport(Expo)
       ExpoHostRuntime.shared.bundleURLOverride = bundleURLOverride
@@ -103,7 +103,7 @@ internal import Expo
   }
 
   /**
-   * Mirrors host manager app delegate API for bare React Native.
+   * Mirrors the host runtime app delegate API, forwarding to Expo or bare React Native as appropriate.
    */
   @objc public func application(
     _ application: UIApplication,

packages/react-native-brownfield/ios/ReactNativeHostRuntime.swift

@@ -31,9 +31,9 @@ class ReactNativeBrownfieldDelegate: RCTDefaultReactNativeFactoryDelegate {
   }
 }
 
-final class ReactNativeHostRuntime: NSObject {
+final class ReactNativeHostRuntime {
   public static let shared = ReactNativeHostRuntime()
-  private var onBundleLoaded: (() -> Void)?
+  private let jsBundleLoadObserver = JSBundleLoadObserver()
   private var delegate = ReactNativeBrownfieldDelegate()
 
   /**
@@ -128,28 +128,7 @@ final class ReactNativeHostRuntime: NSObject {
     self.reactNativeFactory = RCTReactNativeFactory(delegate: delegate)
 
     if let onBundleLoaded {
-      self.onBundleLoaded = onBundleLoaded
-      if RCTIsNewArchEnabled() {
-        NotificationCenter.default.addObserver(
-          self,
-          selector: #selector(jsLoaded),
-          name: NSNotification.Name("RCTInstanceDidLoadBundle"),
-          object: nil
-        )
-      } else {
-        NotificationCenter.default.addObserver(
-          self,
-          selector: #selector(jsLoaded),
-          name: NSNotification.Name("RCTJavaScriptDidLoadNotification"),
-          object: nil
-        )
-      }
+      jsBundleLoadObserver.observeOnce(onBundleLoaded: onBundleLoaded)
     }
   }
-
-  @objc private func jsLoaded(_ notification: Notification) {
-    onBundleLoaded?()
-    onBundleLoaded = nil
-    NotificationCenter.default.removeObserver(self)
-  }
 }