Not even I understand

packages/pigeon/lib/src/dart/dart_generator.dart

@@ -170,7 +170,7 @@ class _FfiType {
       // case 'Float64List':
       //   return 'NSDoubleArray';
       case 'Object':
-        return 'ObjCObjectBase';
+        return 'NSObject';
       case 'List':
         return 'NSMutableArray';
       case 'Map':
@@ -325,7 +325,7 @@ class _FfiType {
             type.baseName == 'bool')) {
       return name;
     }
-    return '_PigeonFfiCodec.writeValue<${ffiType.ffiName}${_getNullableSymbol(type.isNullable)}>($name)';
+    return '_PigeonFfiCodec.writeValue<${ffiType.ffiName}${_getNullableSymbol(type.isNullable && type.baseName != 'Object')}>($name)';
   }
 
   String getFfiCallReturnType(bool forceUnwrap, {bool forceNullable = false}) {
@@ -335,6 +335,9 @@ class _FfiType {
     if (type.baseName == 'List') {
       return 'NSArray?';
     }
+    if (type.baseName == 'Object' && !type.isNullable) {
+      return 'ObjCObjectBase?';
+    }
     return '$ffiName${_getNullableSymbol(forceNullable || type.isNullable)}';
   }
 
@@ -1726,7 +1729,7 @@ class DartGenerator extends StructuredGenerator<InternalDartOptions> {
                 indent.writeln(
                     'final ffi_bridge.${generatorOptions.ffiErrorClassName} error = ffi_bridge.${generatorOptions.ffiErrorClassName}();');
                 indent.writeln(
-                  '$methodCallReturnString${method.isAsynchronous ? 'await ' : ''}_ffiApi.${method.name}${method.parameters.isNotEmpty ? 'With${toUpperCamelCase(method.parameters.first.name)}' : 'WithWrappedError'}(${_getFfiMethodCallArguments(method.parameters)}${method.parameters.isEmpty ? '' : ', wrappedError: '}error);',
+                  '$methodCallReturnString${method.isAsynchronous ? 'await ' : ''}_ffiApi.${method.name}${method.parameters.isNotEmpty ? 'With${toUpperCamelCase(method.parameters.first.name)}' : 'WithWrappedError'}(${_getFfiMethodCallArguments(method.parameters)}${method.parameters.isEmpty ? '' : ', wrappedError: '}error)${returnType.type.baseName == 'Object' && returnType.type.isNullable ? ' as NSObject?' : ''};',
                 );
                 indent.writeScoped('if (error.code != null) {', '}', () {
                   indent.writeln(
@@ -2384,7 +2387,7 @@ ${api.name}({
       }
       if (generatorOptions.useFfi) {
         _writeFfiCodec(indent, root);
-        _writeConvertNSNumberWrapper(indent, root);
+        _writeConvertNumberWrapper(indent, root);
       }
 
       indent.writeln('bool isType<T>(Type t) => T == t;');
@@ -2627,11 +2630,11 @@ class _PigeonJniCodec {
     ''');
   }
 
-  void _writeConvertNSNumberWrapper(Indent indent, Root root) {
+  void _writeConvertNumberWrapper(Indent indent, Root root) {
     indent.newln();
     int typeNum = 4;
     indent.format('''
-      Object? convertNSNumberWrapperToDart(ffi_bridge.NSNumberWrapper value) {
+      Object? convertNumberWrapperToDart(ffi_bridge.NumberWrapper value) {
         switch (value.type) {
           case 1:
             return value.number.longValue;
@@ -2654,18 +2657,18 @@ class _PigeonJniCodec {
 ''');
     typeNum = 4;
     indent.format('''
-      ffi_bridge.NSNumberWrapper convertNSNumberWrapperToFfi(Object value) {
+      ffi_bridge.NumberWrapper convertNumberWrapperToFfi(Object value) {
         switch (value) {
           case int _:
-            return ffi_bridge.NSNumberWrapper.alloc().initWithNumber(NSNumber.alloc().initWithLong(value), type: 1);
+            return ffi_bridge.NumberWrapper.alloc().initWithNumber(NSNumber.alloc().initWithLong(value), type: 1);
           case double _:
-            return ffi_bridge.NSNumberWrapper.alloc().initWithNumber(NSNumber.alloc().initWithDouble(value), type: 2);
+            return ffi_bridge.NumberWrapper.alloc().initWithNumber(NSNumber.alloc().initWithDouble(value), type: 2);
           case bool _:
-            return ffi_bridge.NSNumberWrapper.alloc().initWithNumber(NSNumber.alloc().initWithLong(value ? 1 : 0), type: 3);''');
+            return ffi_bridge.NumberWrapper.alloc().initWithNumber(NSNumber.alloc().initWithLong(value ? 1 : 0), type: 3);''');
     for (final Enum anEnum in root.enums) {
       indent.format('''
         case ${anEnum.name} _:
-          return ffi_bridge.NSNumberWrapper.alloc().initWithNumber(value.toNSNumber(), type: ${typeNum++});''');
+          return ffi_bridge.NumberWrapper.alloc().initWithNumber(value.toNSNumber(), type: ${typeNum++});''');
     }
     indent.format('''
           default:
@@ -2680,7 +2683,7 @@ class _PigeonJniCodec {
     indent.format('''
 class _PigeonFfiCodec {
   static Object? readValue(ObjCObjectBase? value, [Type? outType]) {
-    if (value == null) {
+    if (value == null || ffi_bridge.PigeonInternalNull.isInstance(value)) {
       return null;
     } else if (NSNumber.isInstance(value)) {
       value as NSNumber;
@@ -2735,8 +2738,8 @@ case const (${enumDefinition.name}):
         res[readValue(entry.key)] = readValue(entry.value);
       }
       return res;
-    } else if (ffi_bridge.NSNumberWrapper.isInstance(value)) {
-      return convertNSNumberWrapperToDart(ffi_bridge.NSNumberWrapper.castFrom(value));
+    } else if (ffi_bridge.NumberWrapper.isInstance(value)) {
+      return convertNumberWrapperToDart(ffi_bridge.NumberWrapper.castFrom(value));
     ${root.classes.map((Class dataClass) {
       final _FfiType ffiType = _FfiType.fromClass(dataClass);
       return '''
@@ -2751,10 +2754,14 @@ case const (${enumDefinition.name}):
 
   static T writeValue<T extends ObjCObjectBase?>(Object? value) {
     if (value == null) {
+      final String tString = T.toString();
+      if (tString.contains('ObjCObjectBase') || tString.contains('NSObject')) {
+        return ffi_bridge.PigeonInternalNull() as T;
+      }
       return null as T;
     } else if (value is bool || value is double || value is int || value is Enum) {
       if (T != NSNumber && T.toString() != 'NSNumber?') {
-        return convertNSNumberWrapperToFfi(value) as T;
+        return convertNumberWrapperToFfi(value) as T;
       }
       if (value is bool) {
         return NSNumber.alloc().initWithLong(value ? 1 : 0) as T;
@@ -2768,7 +2775,7 @@ case const (${enumDefinition.name}):
       if (value is Enum) {
         return NSNumber.alloc().initWithLong(value.index) as T;
       }
-      return convertNSNumberWrapperToFfi(value) as T;
+      return convertNumberWrapperToFfi(value) as T;
     } else if (value is String) {
       return NSString(value) as T;
     // } else if (isTypeOrNullableType<NSByteArray>(T)) {
@@ -2808,7 +2815,7 @@ case const (${enumDefinition.name}):
     } else if (value is Map) {
       final NSMutableDictionary res = NSMutableDictionary();
       for (final MapEntry<Object?, Object?> entry in value.entries) {
-        res.setObject(writeValue(entry.value), forKey: writeValue(entry.key));
+        NSMutableDictionary\$Methods(res).setObject(writeValue(entry.value), forKey: NSCopying.castFrom(writeValue(entry.key)));
       }
       return res as T;
     ${root.classes.map((Class dataClass) {

packages/pigeon/lib/src/swift/ffigen_config_generator.dart

@@ -56,7 +56,8 @@ import 'package:swiftgen/swiftgen.dart';
     indent.writeScoped('Future<void> main() async {', '}', () {
       indent.writeScoped('final List<String> classes = <String>[', '];', () {
         indent.inc();
-        indent.writeln("'NSNumberWrapper',");
+        indent.writeln("'PigeonInternalNull',");
+        indent.writeln("'NumberWrapper',");
         for (final Api api in root.apis) {
           if (api is AstHostApi || api is AstFlutterApi) {
             indent.writeln("'${api.name}',");
@@ -115,6 +116,9 @@ import 'package:swiftgen/swiftgen.dart';
           include: (fg.Declaration decl) =>
               classes.contains(decl.originalName) ||
               enums.contains(decl.originalName),
+          module: (fg.Declaration decl) {
+            return decl.originalName.startsWith('NS') ? null : 'test_plugin';
+          }
         ),
       ),
     ),

packages/pigeon/lib/src/swift/swift_generator.dart

@@ -284,6 +284,8 @@ class SwiftGenerator extends StructuredGenerator<InternalSwiftOptions> {
   void _writeFfiCodec(Indent indent, Root root) {
     indent.newln();
     indent.format('''
+@objc class PigeonInternalNull: NSObject {}
+
 @available(iOS 13, macOS 16.0.0, *)
 class _PigeonFfiCodec {
   static func readValue(value: NSObject?, type: String?) -> Any? {
@@ -343,8 +345,8 @@ class _PigeonFfiCodec {
       }
       return res
     } 
-    if (value is NSNumberWrapper) {
-      return unwrapNumber(wrappedNumber: value as! NSNumberWrapper)
+    if (value is NumberWrapper) {
+      return unwrapNumber(wrappedNumber: value as! NumberWrapper)
     }
     if (value is NSString) {
       return value as! NSString
@@ -354,7 +356,7 @@ class _PigeonFfiCodec {
 
   static func writeValue(value: Any?, isObject: Bool = false) -> Any? {
     if (isNullish(value)) {
-      return nil
+      return PigeonInternalNull()
     }
     if (value is Bool || value is Double || value is Int${root.enums.map((Enum enumDefinition) {
       return ' || value is ${enumDefinition.name}';
@@ -802,6 +804,8 @@ if (wrapped == nil) {
         return '_PigeonFfiCodec.writeValue(value: $varName, isObject: true) as${type.isNullable ? '?' : '!'} [NSObject]';
       case 'Map':
         return '_PigeonFfiCodec.writeValue(value: $varName, isObject: true) as${type.isNullable ? '?' : '!'} [NSObject: NSObject]';
+      case 'Object':
+        return '$varName as! NSObject$nullable';
       default:
         return varName;
     }
@@ -1697,11 +1701,12 @@ if (wrapped == nil) {
     }
   }
 
-  void _writeIsNullish(Indent indent) {
+  void _writeIsNullish(Indent indent, {bool useFfi = false}) {
     indent.newln();
     indent.write('private func isNullish(_ value: Any?) -> Bool ');
     indent.addScoped('{', '}', () {
-      indent.writeln('return value is NSNull || value == nil');
+      indent.writeln(
+          'return value is NSNull || value == nil${useFfi ? ' || value is PigeonInternalNull' : ''}');
     });
   }
 
@@ -1767,7 +1772,7 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
 
   void _writeNumberWrapper(Root root, Indent indent) {
     indent.newln();
-    indent.writeScoped('@objc class NSNumberWrapper: NSObject {', '}', () {
+    indent.writeScoped('@objc class NumberWrapper: NSObject {', '}', () {
       indent.writeScoped('@objc init(', ')', () {
         indent.writeln('number: NSNumber,');
         indent.writeln('type: Int,');
@@ -1781,13 +1786,13 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
     });
     indent.newln();
     indent.writeScoped(
-        'private func wrapNumber(number: NSNumber, type: Int) -> NSNumberWrapper {',
+        'private func wrapNumber(number: NSNumber, type: Int) -> NumberWrapper {',
         '}', () {
-      indent.writeln('return NSNumberWrapper(number: number, type: type)');
+      indent.writeln('return NumberWrapper(number: number, type: type)');
     });
     indent.newln();
     indent.writeScoped(
-        'private func unwrapNumber<T>(wrappedNumber: NSNumberWrapper) -> T {',
+        'private func unwrapNumber<T>(wrappedNumber: NumberWrapper) -> T {',
         '}', () {
       indent.writeScoped('switch (wrappedNumber.type) {', '}', () {
         int caseNum = 4;
@@ -1863,7 +1868,7 @@ private func nilOrValue<T>(_ value: Any?) -> T? {
       _writeNumberWrapper(root, indent);
     }
 
-    _writeIsNullish(indent);
+    _writeIsNullish(indent, useFfi: generatorOptions.useFfi);
     _writeNilOrValue(indent);
   }
 

packages/pigeon/pigeons/ni_tests.dart

@@ -46,7 +46,7 @@ class NIAllTypes {
     this.anEnum = NIAnEnum.one,
     this.anotherEnum = NIAnotherEnum.justInCase,
     this.aString = '',
-    // this.anObject = 0,
+    this.anObject = 0,
 
     // Lists
     // This name is in a different format than the others to ensure that name
@@ -82,7 +82,7 @@ class NIAllTypes {
   NIAnEnum anEnum;
   NIAnotherEnum anotherEnum;
   String aString;
-  // Object anObject;
+  Object anObject;
 
   // Lists
   List list;
@@ -201,7 +201,7 @@ class NIAllNullableTypesWithoutRecursion {
 //     this.aNullableEnum,
 //     this.anotherNullableEnum,
     this.aNullableString,
-//     this.aNullableObject,
+    this.aNullableObject,
 
 //     // Lists
 //     // This name is in a different format than the others to ensure that name
@@ -237,7 +237,7 @@ class NIAllNullableTypesWithoutRecursion {
 //   NIAnEnum? aNullableEnum;
 //   NIAnotherEnum? anotherNullableEnum;
   String? aNullableString;
-//   Object? aNullableObject;
+  Object? aNullableObject;
 
 //   // Lists
   List? list;
@@ -534,10 +534,10 @@ abstract class NIHostIntegrationCoreApi {
   // @SwiftFunction('echo(_:)')
   // Float64List? echoNullableFloat64List(Float64List? aNullableFloat64List);
 
-  // /// Returns the passed in generic Object.
-  // @ObjCSelector('echoNullableObject:')
+  /// Returns the passed in generic Object.
+  @ObjCSelector('echoNullableObject:')
   // @SwiftFunction('echo(_:)')
-  // Object? echoNullableObject(Object? aNullableObject);
+  Object? echoNullableObject(Object? aNullableObject);
 
   /// Returns the passed list, to test serialization and deserialization.
   @ObjCSelector('echoNullableList:')

packages/pigeon/platform_tests/shared_test_plugin_code/lib/example_app.dart

@@ -44,7 +44,8 @@ class _ExampleAppState extends State<ExampleApp> {
       // final NIHostIntegrationCoreApiForNativeInterop? api =
       //     NIHostIntegrationCoreApiForNativeInterop.getInstance();
       // api!.noop();
-      // api.echoAllTypes(genericNIAllTypes);
+      // api.echoAllNullableTypesWithoutRecursion(
+      //     genericNIAllNullableTypesWithoutRecursion);
     } catch (e) {
       setState(() {
         status = 'Failed: $e';

packages/pigeon/platform_tests/shared_test_plugin_code/lib/ni_test_types.dart

@@ -282,7 +282,7 @@ final NIAllNullableTypesWithoutRecursion
   // aNullable8ByteArray: Int64List.fromList(<int>[7, 8, 9]),
   // aNullableFloatArray: Float64List.fromList(<double>[2.71828, doublePi]),
   // aNullableEnum: NIAnEnum.fourHundredTwentyTwo,
-  // aNullableObject: 0,
+  aNullableObject: 'nullable',
   list: list,
   // stringList: stringList,
   // intList: intList,
@@ -328,7 +328,7 @@ final NIAllTypes genericNIAllTypes = NIAllTypes(
   // a8ByteArray: Int64List.fromList(<int>[7, 8, 9]),
   // aFloatArray: Float64List.fromList(<double>[2.71828, doublePi]),
   anEnum: NIAnEnum.fortyTwo,
-  // anObject: 1,
+  anObject: 'notNullable',
   list: nonNullList,
   // stringList: nonNullStringList,
   // intList: nonNullIntList,