[ffigen] Add the ability to get a pointer to an objective C object (#568)

diff --git a/pkgs/ffigen/lib/src/code_generator/objc_block.dart b/pkgs/ffigen/lib/src/code_generator/objc_block.dart
index 310fef1..1599748 100644
--- a/pkgs/ffigen/lib/src/code_generator/objc_block.dart
+++ b/pkgs/ffigen/lib/src/code_generator/objc_block.dart

@@ -139,9 +139,6 @@
     s.write(''');
   }''');
 
-    // Get the pointer to the underlying block.
-    s.write('  ${blockPtr.getCType(w)} get pointer => _id;\n');
-
     s.write('}\n');
     return BindingString(
         type: BindingStringType.objcBlock, string: s.toString());

diff --git a/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart b/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart
index ebb4b20..05cd130 100644
--- a/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart
+++ b/pkgs/ffigen/lib/src/code_generator/objc_built_in_functions.dart

@@ -242,6 +242,9 @@
 
   @override
   int get hashCode => _id.hashCode;
+
+  /// Return a pointer to this object.
+  $idType get pointer => _id;
 }
 ''');
   }

diff --git a/pkgs/ffigen/test/native_objc_test/cast_test.dart b/pkgs/ffigen/test/native_objc_test/cast_test.dart
index 55b787b..c63d940 100644
--- a/pkgs/ffigen/test/native_objc_test/cast_test.dart
+++ b/pkgs/ffigen/test/native_objc_test/cast_test.dart

@@ -40,6 +40,11 @@
       expect(fromCast, testInstance!);
     });
 
+    test('pointers are equal', () {
+      final meAsInt = testInstance!.meAsInt();
+      expect(testInstance!.pointer.address, meAsInt);
+    });
+
     test('equality equals', () {
       final meAsInt = testInstance!.meAsInt();
       final fromCast = Castaway.castFromPointer(