[macOS] Add lookupKeyForAsset to FlutterPluginRegistrar (flutter/engine#37421)

Fixes https://github.com/flutter/flutter/issues/47681

[C++, Objective-C, Java style guides]: https://github.com/flutter/engine/blob/main/CONTRIBUTING.md#style

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -2464,11 +2464,14 @@ ORIGIN: ../../../flutter/shell/platform/darwin/common/command_line.mm + ../../..
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterBinaryMessenger.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterChannels.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterCodecs.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterDartProject.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterTexture.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterChannels.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterChannelsTest.m + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterStandardCodec.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterStandardCodecHelper.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterStandardCodecHelper.h + ../../../flutter/LICENSE
@@ -2482,7 +2485,6 @@ ORIGIN: ../../../flutter/shell/platform/darwin/graphics/FlutterDarwinExternalTex
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/Flutter.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterAppDelegate.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterCallbackCache.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterDartProject.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterEngine.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterEngineGroup.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterHeadlessDartRunner.h + ../../../flutter/LICENSE
@@ -2618,7 +2620,6 @@ ORIGIN: ../../../flutter/shell/platform/darwin/ios/platform_view_ios.mm + ../../
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/rendering_api_selection.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/ios/rendering_api_selection.mm + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterAppDelegate.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterDartProject.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterEngine.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterMacOS.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterPlatformViews.h + ../../../flutter/LICENSE
@@ -5069,11 +5070,14 @@ FILE: ../../../flutter/shell/platform/darwin/common/command_line.mm
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterBinaryMessenger.h
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterChannels.h
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterCodecs.h
+FILE: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterDartProject.h
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterMacros.h
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Headers/FlutterTexture.h
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterChannels.mm
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterChannelsTest.m
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterCodecs.mm
+FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.h
+FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.mm
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterStandardCodec.mm
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterStandardCodecHelper.cc
 FILE: ../../../flutter/shell/platform/darwin/common/framework/Source/FlutterStandardCodecHelper.h
@@ -5087,7 +5091,6 @@ FILE: ../../../flutter/shell/platform/darwin/graphics/FlutterDarwinExternalTextu
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/Flutter.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterAppDelegate.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterCallbackCache.h
-FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterDartProject.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterEngine.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterEngineGroup.h
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Headers/FlutterHeadlessDartRunner.h
@@ -5225,7 +5228,6 @@ FILE: ../../../flutter/shell/platform/darwin/ios/platform_view_ios.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/rendering_api_selection.h
 FILE: ../../../flutter/shell/platform/darwin/ios/rendering_api_selection.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterAppDelegate.h
-FILE: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterDartProject.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterEngine.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterMacOS.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Headers/FlutterPlatformViews.h

engine/src/flutter/shell/platform/darwin/common/BUILD.gn

@@ -36,6 +36,8 @@ source_set("framework_shared") {
   sources = [
     "framework/Source/FlutterChannels.mm",
     "framework/Source/FlutterCodecs.mm",
+    "framework/Source/FlutterNSBundleUtils.h",
+    "framework/Source/FlutterNSBundleUtils.mm",
     "framework/Source/FlutterStandardCodec.mm",
     "framework/Source/FlutterStandardCodecHelper.cc",
     "framework/Source/FlutterStandardCodec_Internal.h",
@@ -43,6 +45,8 @@ source_set("framework_shared") {
 
   public = framework_shared_headers
 
+  public += [ "framework/Source/FlutterNSBundleUtils.h" ]
+
   defines = [ "FLUTTER_FRAMEWORK" ]
 
   public_configs = [

engine/src/flutter/shell/platform/darwin/common/framework/Headers/FlutterDartProject.h

@@ -6,6 +6,7 @@
 #define FLUTTER_FLUTTERDARTPROJECT_H_
 
 #import <Foundation/Foundation.h>
+#import <TargetConditionals.h>
 
 #import "FlutterMacros.h"
 
@@ -13,25 +14,49 @@ NS_ASSUME_NONNULL_BEGIN
 
 /**
  * A set of Flutter and Dart assets used by a `FlutterEngine` to initialize execution.
+ *
  */
 FLUTTER_DARWIN_EXPORT
 @interface FlutterDartProject : NSObject
 
 /**
  * Initializes a Flutter Dart project from a bundle.
+ *
+ * The bundle must either contain a flutter_assets resource directory, or set the Info.plist key
+ * FLTAssetsPath to override that name (if you are doing a custom build using a different name).
+ *
+ * @param bundle The bundle containing the Flutter assets directory. If nil, the App framework
+ *               created by Flutter will be used.
  */
 - (instancetype)initWithPrecompiledDartBundle:(nullable NSBundle*)bundle NS_DESIGNATED_INITIALIZER;
-
 /**
  * Unavailable - use `init` instead.
  */
-- (instancetype)initFromDefaultSourceForConfiguration FLUTTER_UNAVAILABLE("Use -init instead.");
+- (instancetype)initFromDefaultSourceForConfiguration API_UNAVAILABLE(macos)
+    FLUTTER_UNAVAILABLE("Use -init instead.");
+
+/**
+ * Returns the default identifier for the bundle where we expect to find the Flutter Dart
+ * application.
+ */
++ (NSString*)defaultBundleIdentifier;
+
+/**
+ * An NSArray of NSStrings to be passed as command line arguments to the Dart entrypoint.
+ *
+ * If this is not explicitly set, this will default to the contents of
+ * [NSProcessInfo arguments], without the binary name.
+ *
+ * Set this to nil to pass no arguments to the Dart entrypoint.
+ */
+@property(nonatomic, nullable, copy)
+    NSArray<NSString*>* dartEntrypointArguments API_UNAVAILABLE(ios);
 
 /**
  * Returns the file name for the given asset. If the bundle with the identifier
  * "io.flutter.flutter.app" exists, it will try use that bundle; otherwise, it
  * will use the main bundle.  To specify a different bundle, use
- * `-lookupKeyForAsset:asset:fromBundle`.
+ * `+lookupKeyForAsset:fromBundle`.
  *
  * @param asset The name of the asset. The name can be hierarchical.
  * @return the file name to be used for lookup in the main bundle.
@@ -71,12 +96,6 @@ FLUTTER_DARWIN_EXPORT
                    fromPackage:(NSString*)package
                     fromBundle:(nullable NSBundle*)bundle;
 
-/**
- * Returns the default identifier for the bundle where we expect to find the Flutter Dart
- * application.
- */
-+ (NSString*)defaultBundleIdentifier;
-
 @end
 
 NS_ASSUME_NONNULL_END

engine/src/flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.h

@@ -0,0 +1,35 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SHELL_PLATFORM_DARWIN_COMMON_FRAMEWORK_SOURCE_FLUTTERNSBUNDLEUTILS_H_
+#define SHELL_PLATFORM_DARWIN_COMMON_FRAMEWORK_SOURCE_FLUTTERNSBUNDLEUTILS_H_
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+// Finds a bundle with the named `bundleID` within `searchURL`.
+//
+// Returns `nil` if the bundle cannot be found or if errors are encountered.
+NSBundle* FLTFrameworkBundleInternal(NSString* bundleID, NSURL* searchURL);
+
+// Finds a bundle with the named `bundleID`.
+//
+// `+[NSBundle bundleWithIdentifier:]` is slow, and can take in the order of
+// tens of milliseconds in a minimal flutter app, and closer to 100 milliseconds
+// in a medium sized Flutter app on an iPhone 13. It is likely that the slowness
+// comes from having to traverse and load all bundles known to the process.
+// Using `+[NSBundle allframeworks]` and filtering also suffers from the same
+// problem.
+//
+// This implementation is an optimization to first limit the search space to
+// `+[NSBundle privateFrameworksURL]` of the main bundle, which is usually where
+// frameworks used by this file are placed. If the desired bundle cannot be
+// found here, the implementation falls back to
+// `+[NSBundle bundleWithIdentifier:]`.
+NSBundle* FLTFrameworkBundleWithIdentifier(NSString* bundleID);
+
+NS_ASSUME_NONNULL_END
+
+#endif  // SHELL_PLATFORM_DARWIN_COMMON_FRAMEWORK_SOURCE_FLUTTERNSBUNDLEUTILS_H_

engine/src/flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.mm

@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <Foundation/Foundation.h>
+
+NSBundle* FLTFrameworkBundleInternal(NSString* bundleID, NSURL* searchURL) {
+  NSDirectoryEnumerator<NSURL*>* frameworkEnumerator = [NSFileManager.defaultManager
+                 enumeratorAtURL:searchURL
+      includingPropertiesForKeys:nil
+                         options:NSDirectoryEnumerationSkipsSubdirectoryDescendants |
+                                 NSDirectoryEnumerationSkipsHiddenFiles
+                    // Skip directories where errors are encountered.
+                    errorHandler:nil];
+
+  for (NSURL* candidate in frameworkEnumerator) {
+    NSBundle* bundle = [NSBundle bundleWithURL:candidate];
+    if ([bundle.bundleIdentifier isEqualToString:bundleID]) {
+      return bundle;
+    }
+  }
+  return nil;
+}
+
+NSBundle* FLTFrameworkBundleWithIdentifier(NSString* bundleID) {
+  NSBundle* bundle = FLTFrameworkBundleInternal(bundleID, NSBundle.mainBundle.privateFrameworksURL);
+  if (bundle != nil) {
+    return bundle;
+  }
+  // Fallback to slow implementation.
+  return [NSBundle bundleWithIdentifier:bundleID];
+}

engine/src/flutter/shell/platform/darwin/common/framework_shared.gni

@@ -9,5 +9,6 @@ framework_shared_headers =
                     "framework/Headers/FlutterChannels.h",
                     "framework/Headers/FlutterCodecs.h",
                     "framework/Headers/FlutterTexture.h",
+                    "framework/Headers/FlutterDartProject.h",
                   ],
                   "abspath")

engine/src/flutter/shell/platform/darwin/ios/BUILD.gn

@@ -27,7 +27,6 @@ _flutter_framework_headers = [
   "framework/Headers/Flutter.h",
   "framework/Headers/FlutterAppDelegate.h",
   "framework/Headers/FlutterCallbackCache.h",
-  "framework/Headers/FlutterDartProject.h",
   "framework/Headers/FlutterEngine.h",
   "framework/Headers/FlutterEngineGroup.h",
   "framework/Headers/FlutterHeadlessDartRunner.h",

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterDartProject.mm

@@ -32,50 +32,6 @@ extern const intptr_t kPlatformStrongDillSize;
 
 static const char* kApplicationKernelSnapshotFileName = "kernel_blob.bin";
 
-// Finds a bundle with the named `bundleID` within `searchURL`.
-//
-// Returns `nil` if the bundle cannot be found or if errors are encountered.
-NSBundle* FLTFrameworkBundleInternal(NSString* bundleID, NSURL* searchURL) {
-  NSDirectoryEnumerator<NSURL*>* frameworkEnumerator = [NSFileManager.defaultManager
-                 enumeratorAtURL:searchURL
-      includingPropertiesForKeys:nil
-                         options:NSDirectoryEnumerationSkipsSubdirectoryDescendants |
-                                 NSDirectoryEnumerationSkipsHiddenFiles
-                    // Skip directories where errors are encountered.
-                    errorHandler:nil];
-
-  for (NSURL* candidate in frameworkEnumerator) {
-    NSBundle* bundle = [NSBundle bundleWithURL:candidate];
-    if ([bundle.bundleIdentifier isEqualToString:bundleID]) {
-      return bundle;
-    }
-  }
-  return nil;
-}
-
-// Finds a bundle with the named `bundleID`.
-//
-// `+[NSBundle bundleWithIdentifier:]` is slow, and can take in the order of
-// tens of milliseconds in a minimal flutter app, and closer to 100 milliseconds
-// in a medium sized Flutter app on an iPhone 13. It is likely that the slowness
-// comes from having to traverse and load all bundles known to the process.
-// Using `+[NSBundle allframeworks]` and filtering also suffers from the same
-// problem.
-//
-// This implementation is an optimization to first limit the search space to
-// `+[NSBundle privateFrameworksURL]` of the main bundle, which is usually where
-// frameworks used by this file are placed. If the desired bundle cannot be
-// found here, the implementation falls back to
-// `+[NSBundle bundleWithIdentifier:]`.
-NS_INLINE NSBundle* FLTFrameworkBundleWithIdentifier(NSString* bundleID) {
-  NSBundle* bundle = FLTFrameworkBundleInternal(bundleID, NSBundle.mainBundle.privateFrameworksURL);
-  if (bundle != nil) {
-    return bundle;
-  }
-  // Fallback to slow implementation.
-  return [NSBundle bundleWithIdentifier:bundleID];
-}
-
 flutter::Settings FLTDefaultSettingsForBundle(NSBundle* bundle, NSProcessInfo* processInfoOrNil) {
   auto command_line = flutter::CommandLineFromNSProcessInfo(processInfoOrNil);
 
@@ -286,6 +242,11 @@ flutter::Settings FLTDefaultSettingsForBundle(NSBundle* bundle, NSProcessInfo* p
   flutter::Settings _settings;
 }
 
+// This property is marked unavailable on iOS in the common header.
+// That doesn't seem to be enough to prevent this property from being synthesized.
+// Mark dynamic to avoid warnings.
+@dynamic dartEntrypointArguments;
+
 #pragma mark - Override base class designated initializers
 
 - (instancetype)init {

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterDartProject_Internal.h

@@ -8,12 +8,11 @@
 #include "flutter/common/settings.h"
 #include "flutter/runtime/platform_data.h"
 #include "flutter/shell/common/engine.h"
-#import "flutter/shell/platform/darwin/ios/framework/Headers/FlutterDartProject.h"
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterDartProject.h"
+#import "flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-NSBundle* FLTFrameworkBundleInternal(NSString* bundleID, NSURL* searchURL);
-
 flutter::Settings FLTDefaultSettingsForBundle(NSBundle* _Nullable bundle = nil,
                                               NSProcessInfo* _Nullable processInfoOrNil = nil);
 

engine/src/flutter/shell/platform/darwin/macos/BUILD.gn

@@ -38,7 +38,6 @@ _framework_binary_subpath = "Versions/A/$_flutter_framework_name"
 # the Flutter engine source root.
 _flutter_framework_headers = [
   "framework/Headers/FlutterAppDelegate.h",
-  "framework/Headers/FlutterDartProject.h",
   "framework/Headers/FlutterEngine.h",
   "framework/Headers/FlutterMacOS.h",
   "framework/Headers/FlutterPlatformViews.h",

engine/src/flutter/shell/platform/darwin/macos/framework/Headers/FlutterDartProject.h

@@ -1,44 +0,0 @@
-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef FLUTTER_FLUTTERDARTPROJECT_H_
-#define FLUTTER_FLUTTERDARTPROJECT_H_
-
-#import <Foundation/Foundation.h>
-
-#import "FlutterMacros.h"
-
-/**
- * A set of Flutter and Dart assets used by a `FlutterEngine` to initialize execution.
- *
- * TODO(stuartmorgan): Align API with FlutterDartProject, and combine.
- */
-FLUTTER_DARWIN_EXPORT
-@interface FlutterDartProject : NSObject
-
-/**
- * Initializes a Flutter Dart project from a bundle.
- *
- * The bundle must either contain a flutter_assets resource directory, or set the Info.plist key
- * FLTAssetsPath to override that name (if you are doing a custom build using a different name).
- *
- * @param bundle The bundle containing the Flutter assets directory. If nil, the App framework
- *               created by Flutter will be used.
- */
-- (nonnull instancetype)initWithPrecompiledDartBundle:(nullable NSBundle*)bundle
-    NS_DESIGNATED_INITIALIZER;
-
-/**
- * An NSArray of NSStrings to be passed as command line arguments to the Dart entrypoint.
- *
- * If this is not explicitly set, this will default to the contents of
- * [NSProcessInfo arguments], without the binary name.
- *
- * Set this to nil to pass no arguments to the Dart entrypoint.
- */
-@property(nonatomic, nullable, copy) NSArray<NSString*>* dartEntrypointArguments;
-
-@end
-
-#endif  // FLUTTER_FLUTTERDARTPROJECT_H_

engine/src/flutter/shell/platform/darwin/macos/framework/Headers/FlutterPluginRegistrarMacOS.h

@@ -67,6 +67,27 @@ FLUTTER_DARWIN_EXPORT
 - (void)registerViewFactory:(nonnull NSObject<FlutterPlatformViewFactory>*)factory
                      withId:(nonnull NSString*)factoryId;
 
+/**
+ * Returns the file name for the given asset.
+ * The returned file name can be used to access the asset in the application's main bundle.
+ *
+ * @param asset The name of the asset. The name can be hierarchical.
+ * @return the file name to be used for lookup in the main bundle.
+ */
+- (nonnull NSString*)lookupKeyForAsset:(nonnull NSString*)asset;
+
+/**
+ * Returns the file name for the given asset which originates from the specified package.
+ * The returned file name can be used to access the asset in the application's main bundle.
+ *
+ *
+ * @param asset The name of the asset. The name can be hierarchical.
+ * @param package The name of the package from which the asset originates.
+ * @return the file name to be used for lookup in the main bundle.
+ */
+- (nonnull NSString*)lookupKeyForAsset:(nonnull NSString*)asset
+                           fromPackage:(nonnull NSString*)package;
+
 @end
 
 /**

engine/src/flutter/shell/platform/darwin/macos/framework/Headers/FlutterViewController.h

@@ -117,6 +117,29 @@ FLUTTER_DARWIN_EXPORT
  */
 - (void)onPreEngineRestart;
 
+/**
+ * Returns the file name for the given asset.
+ * The returned file name can be used to access the asset in the application's
+ * main bundle.
+ *
+ * @param asset The name of the asset. The name can be hierarchical.
+ * @return The file name to be used for lookup in the main bundle.
+ */
+- (nonnull NSString*)lookupKeyForAsset:(nonnull NSString*)asset;
+
+/**
+ * Returns the file name for the given asset which originates from the specified
+ * package.
+ * The returned file name can be used to access the asset in the application's
+ * main bundle.
+ *
+ * @param asset The name of the asset. The name can be hierarchical.
+ * @param package The name of the package from which the asset originates.
+ * @return The file name to be used for lookup in the main bundle.
+ */
+- (nonnull NSString*)lookupKeyForAsset:(nonnull NSString*)asset
+                           fromPackage:(nonnull NSString*)package;
+
 /**
  * The contentView (FlutterView)'s background color is set to black during
  * its instantiation.

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject.mm

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#import "flutter/shell/platform/darwin/macos/framework/Headers/FlutterDartProject.h"
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterDartProject.h"
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject_Internal.h"
 
 #include <vector>
@@ -12,6 +12,15 @@
 static NSString* const kICUBundlePath = @"icudtl.dat";
 static NSString* const kAppBundleIdentifier = @"io.flutter.flutter.app";
 
+#pragma mark - Private interface declaration.
+@interface FlutterDartProject ()
+/**
+ Get the Flutter assets name path by pass the bundle. If bundle is nil, we use the main bundle as
+ default.
+ */
++ (NSString*)flutterAssetsNameWithBundle:(NSBundle*)bundle;
+@end
+
 @implementation FlutterDartProject {
   NSBundle* _dartBundle;
   NSString* _assetsPath;
@@ -26,7 +35,7 @@ static NSString* const kAppBundleIdentifier = @"io.flutter.flutter.app";
   self = [super init];
   NSAssert(self, @"Super init cannot be nil");
 
-  _dartBundle = bundle ?: [NSBundle bundleWithIdentifier:kAppBundleIdentifier];
+  _dartBundle = bundle ?: FLTFrameworkBundleWithIdentifier(kAppBundleIdentifier);
   if (_dartBundle == nil) {
     // The bundle isn't loaded and can't be found by bundle ID. Find it by path.
     _dartBundle = [NSBundle bundleWithURL:[NSBundle.mainBundle.privateFrameworksURL
@@ -81,4 +90,42 @@ static NSString* const kAppBundleIdentifier = @"io.flutter.flutter.app";
   return path;
 }
 
++ (NSString*)flutterAssetsNameWithBundle:(NSBundle*)bundle {
+  if (bundle == nil) {
+    bundle = FLTFrameworkBundleWithIdentifier(kAppBundleIdentifier);
+  }
+  if (bundle == nil) {
+    bundle = [NSBundle mainBundle];
+  }
+  NSString* flutterAssetsName = [bundle objectForInfoDictionaryKey:@"FLTAssetsPath"];
+  if (flutterAssetsName == nil) {
+    flutterAssetsName = @"Contents/Frameworks/App.framework/Resources/flutter_assets";
+  }
+  return flutterAssetsName;
+}
+
++ (NSString*)lookupKeyForAsset:(NSString*)asset {
+  return [self lookupKeyForAsset:asset fromBundle:nil];
+}
+
++ (NSString*)lookupKeyForAsset:(NSString*)asset fromBundle:(nullable NSBundle*)bundle {
+  NSString* flutterAssetsName = [FlutterDartProject flutterAssetsNameWithBundle:bundle];
+  return [NSString stringWithFormat:@"%@/%@", flutterAssetsName, asset];
+}
+
++ (NSString*)lookupKeyForAsset:(NSString*)asset fromPackage:(NSString*)package {
+  return [self lookupKeyForAsset:asset fromPackage:package fromBundle:nil];
+}
+
++ (NSString*)lookupKeyForAsset:(NSString*)asset
+                   fromPackage:(NSString*)package
+                    fromBundle:(nullable NSBundle*)bundle {
+  return [self lookupKeyForAsset:[NSString stringWithFormat:@"packages/%@/%@", package, asset]
+                      fromBundle:bundle];
+}
+
++ (NSString*)defaultBundleIdentifier {
+  return kAppBundleIdentifier;
+}
+
 @end

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject_Internal.h

@@ -5,7 +5,8 @@
 #ifndef SHELL_PLATFORM_DARWIN_MACOS_FRAMEWORK_SOURCE_FLUTTERDARTPROJECT_INTERNAL_H_
 #define SHELL_PLATFORM_DARWIN_MACOS_FRAMEWORK_SOURCE_FLUTTERDARTPROJECT_INTERNAL_H_
 
-#import "flutter/shell/platform/darwin/macos/framework/Headers/FlutterDartProject.h"
+#import "flutter/shell/platform/darwin/common/framework/Headers/FlutterDartProject.h"
+#import "flutter/shell/platform/darwin/common/framework/Source/FlutterNSBundleUtils.h"
 
 #include <string>
 #include <vector>

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterEngine.mm

@@ -314,6 +314,14 @@ constexpr char kTextPlainFormat[] = "text/plain";
   [[_flutterEngine platformViewController] registerViewFactory:factory withId:factoryId];
 }
 
+- (NSString*)lookupKeyForAsset:(NSString*)asset {
+  return [FlutterDartProject lookupKeyForAsset:asset];
+}
+
+- (NSString*)lookupKeyForAsset:(NSString*)asset fromPackage:(NSString*)package {
+  return [FlutterDartProject lookupKeyForAsset:asset fromPackage:package];
+}
+
 @end
 
 // Callbacks provided to the engine. See the called methods for documentation.

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController.mm

@@ -866,6 +866,14 @@ static void CommonInit(FlutterViewController* controller, FlutterEngine* engine)
   }
 }
 
+- (NSString*)lookupKeyForAsset:(NSString*)asset {
+  return [FlutterDartProject lookupKeyForAsset:asset];
+}
+
+- (NSString*)lookupKeyForAsset:(NSString*)asset fromPackage:(NSString*)package {
+  return [FlutterDartProject lookupKeyForAsset:asset fromPackage:package];
+}
+
 #pragma mark - FlutterViewReshapeListener
 
 /**

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewControllerTest.mm

@@ -67,6 +67,8 @@
 - (bool)testModifierKeysAreSynthesizedOnMouseMove;
 - (bool)testViewWillAppearCalledMultipleTimes;
 - (bool)testFlutterViewIsConfigured;
+- (bool)testLookupKeyAssets;
+- (bool)testLookupKeyAssetsWithPackage;
 
 + (void)respondFalseForSendEvent:(const FlutterKeyEvent&)event
                         callback:(nullable FlutterKeyEventCallback)callback
@@ -241,6 +243,14 @@ TEST(FlutterViewControllerTest, testFlutterViewIsConfigured) {
   ASSERT_TRUE([[FlutterViewControllerTestObjC alloc] testFlutterViewIsConfigured]);
 }
 
+TEST(FlutterViewControllerTest, testLookupKeyAssets) {
+  ASSERT_TRUE([[FlutterViewControllerTestObjC alloc] testLookupKeyAssets]);
+}
+
+TEST(FlutterViewControllerTest, testLookupKeyAssetsWithPackage) {
+  ASSERT_TRUE([[FlutterViewControllerTestObjC alloc] testLookupKeyAssetsWithPackage]);
+}
+
 }  // namespace flutter::testing
 
 #pragma mark - FlutterViewControllerTestObjC
@@ -876,6 +886,24 @@ TEST(FlutterViewControllerTest, testFlutterViewIsConfigured) {
   return true;
 }
 
+- (bool)testLookupKeyAssets {
+  FlutterViewController* viewController = [[FlutterViewController alloc] initWithProject:nil];
+  NSString* key = [viewController lookupKeyForAsset:@"test.png"];
+  EXPECT_TRUE(
+      [key isEqualToString:@"Contents/Frameworks/App.framework/Resources/flutter_assets/test.png"]);
+  return true;
+}
+
+- (bool)testLookupKeyAssetsWithPackage {
+  FlutterViewController* viewController = [[FlutterViewController alloc] initWithProject:nil];
+
+  NSString* packageKey = [viewController lookupKeyForAsset:@"test.png" fromPackage:@"test"];
+  EXPECT_TRUE([packageKey
+      isEqualToString:
+          @"Contents/Frameworks/App.framework/Resources/flutter_assets/packages/test/test.png"]);
+  return true;
+}
+
 static void SwizzledNoop(id self, SEL _cmd) {}
 
 // Verify workaround an AppKit bug where mouseDown/mouseUp are not called on the view controller if
@@ -918,6 +946,7 @@ static void SwizzledNoop(id self, SEL _cmd) {}
   // Restore the original NSResponder mouseDown/mouseUp implementations.
   method_setImplementation(mouseDown, origMouseDown);
   method_setImplementation(mouseUp, origMouseUp);
+
   return true;
 }