[iOS] Add a native module for Expo Go (expo#23730)

ios/Exponent/Versioned/Core/Modules/ExpoGoModule.swift

@@ -1,14 +1,28 @@
 // Copyright 2023-present 650 Industries. All rights reserved.
 
 import ExpoModulesCore
+import EXManifests
 
 final class ExpoGoModule: Module {
+  let manifest: Manifest
+
+  // swiftlint:disable:next unavailable_function
+  required init(appContext: AppContext) {
+    fatalError("Initializer not implemented, use init(appContext:params:manifest:) instead")
+  }
+
+  init(appContext: AppContext, manifest: Manifest) {
+    self.manifest = manifest
+    super.init(appContext: appContext)
+  }
+
   func definition() -> ModuleDefinition {
-    Name("ExpoGoModule")
+    Name("ExpoGo")
 
     Constants {
       return [
-        "isDetached": false
+        "expoVersion": Bundle.main.object(forInfoDictionaryKey: "CFBundleVersion"),
+        "projectConfig": manifest.expoGoConfigRootObject()
       ]
     }
   }

ios/Exponent/Versioned/Core/VersionManager.swift

@@ -87,7 +87,11 @@ final class VersionManager: EXVersionManagerObjC {
    Registers Expo modules that are not generated in ``ExpoModulesProvider``, but are necessary for Expo Go apps.
    */
   private func registerExpoModules() {
-    appContext?.moduleRegistry.register(moduleType: ExpoGoModule.self)
+    guard let appContext else {
+      log.error("Unable to register Expo modules, the app context is unavailable")
+      return
+    }
+    appContext.moduleRegistry.register(module: ExpoGoModule(appContext: appContext, manifest: manifest))
   }
 }
 

packages/expo-manifests/ios/EXManifests/BaseLegacyManifest.swift

@@ -5,11 +5,11 @@ import Foundation
 @objc(EXManifestBaseLegacyManifest)
 @objcMembers
 public class BaseLegacyManifest: Manifest {
-  override func expoClientConfigRootObject() -> [String: Any]? {
+  public override func expoClientConfigRootObject() -> [String: Any]? {
     return rawManifestJSON()
   }
 
-  override func expoGoConfigRootObject() -> [String: Any]? {
+  public override func expoGoConfigRootObject() -> [String: Any]? {
     return rawManifestJSON()
   }
 

packages/expo-manifests/ios/EXManifests/Manifest.swift

@@ -119,11 +119,11 @@ public class Manifest: NSObject {
     preconditionFailure("Must override in concrete class")
   }
 
-  func expoGoConfigRootObject() -> [String: Any]? {
+  public func expoGoConfigRootObject() -> [String: Any]? {
     preconditionFailure("Must override in concrete class")
   }
 
-  func expoClientConfigRootObject() -> [String: Any]? {
+  public func expoClientConfigRootObject() -> [String: Any]? {
     preconditionFailure("Must override in concrete class")
   }
 

packages/expo-manifests/ios/EXManifests/NewManifest.swift

@@ -73,11 +73,11 @@ public class NewManifest: Manifest {
     return launchAsset().requiredValue(forKey: "url")
   }
 
-  override func expoClientConfigRootObject() -> [String: Any]? {
+  public override func expoClientConfigRootObject() -> [String: Any]? {
     return extra()?.optionalValue(forKey: "expoClient")
   }
 
-  override func expoGoConfigRootObject() -> [String: Any]? {
+  public override func expoGoConfigRootObject() -> [String: Any]? {
     return extra()?.optionalValue(forKey: "expoGo")
   }
 }

packages/expo-modules-core/ios/Swift/ModuleRegistry.swift

@@ -17,16 +17,26 @@ public final class ModuleRegistry: Sequence {
     registry[holder.name] = holder
   }
 
+  /**
+   Registers an instance of the module.
+   */
+  public func register(module: AnyModule) {
+    guard let appContext else {
+      log.error("Unable to register a module '\(module)', the app context is unavailable")
+      return
+    }
+    register(holder: ModuleHolder(appContext: appContext, module: module))
+  }
+
   /**
    Registers a module by its type.
    */
   public func register(moduleType: AnyModule.Type) {
-    guard let appContext = appContext else {
+    guard let appContext else {
+      log.error("Unable to register a module '\(moduleType)', the app context is unavailable")
       return
     }
-    let module = moduleType.init(appContext: appContext)
-    let holder = ModuleHolder(appContext: appContext, module: module)
-    register(holder: holder)
+    register(module: moduleType.init(appContext: appContext))
   }
 
   /**

packages/expo/src/Expo.ts

@@ -5,3 +5,4 @@ import * as Logs from './logs/Logs';
 export { Logs };
 export { disableErrorHandling } from './errors/ExpoErrorManager';
 export { default as registerRootComponent } from './launch/registerRootComponent';
+export { isRunningInExpoGo, getExpoGoProjectConfig } from './environment/ExpoGo';

packages/expo/src/environment/ExpoGo.ts

@@ -0,0 +1,52 @@
+import { requireNativeModule } from 'expo-modules-core';
+
+type ExpoGoModule = {
+  expoVersion: string;
+  projectConfig: ExpoGoProjectConfig;
+};
+
+type ExpoGoProjectConfig = {
+  mainModuleName?: string;
+  debuggerHost?: string;
+  logUrl?: string;
+  developer?: {
+    tool?: string;
+    [key: string]: any;
+  };
+  packagerOpts?: ExpoGoPackagerOpts;
+};
+
+type ExpoGoPackagerOpts = {
+  hostType?: string;
+  dev?: boolean;
+  strict?: boolean;
+  minify?: boolean;
+  urlType?: string;
+  urlRandomness?: string;
+  lanType?: string;
+  [key: string]: any;
+};
+
+// ExpoGo module is available only when the app is run in Expo Go,
+// otherwise we use `null` instead of throwing an error.
+const NativeExpoGoModule = ((): ExpoGoModule | null => {
+  try {
+    return requireNativeModule('ExpoGo');
+  } catch {
+    return null;
+  }
+})();
+
+/**
+ * Returns a boolean value whether the app is running in Expo Go.
+ */
+export function isRunningInExpoGo(): boolean {
+  return NativeExpoGoModule != null;
+}
+
+/**
+ * Returns an Expo Go project config from the manifest or `null` if the app is not running in Expo Go.
+ */
+export function getExpoGoProjectConfig(): ExpoGoProjectConfig | null {
+  return NativeExpoGoModule?.projectConfig ?? null;
+}