From 8cf3a854be47d1b37f6d73d486473b7bd6805f99 Mon Sep 17 00:00:00 2001
From: Harald <harald.achitz@gmail.com>
Date: Sun, 10 Jul 2022 20:45:57 +0200
Subject: [PATCH] Make NSObject based protocols optional (#134)

This PR does fix #133 for now.

* Add new bool toggle --objc-strict-protocols
* Enables / disables the <NSObject> tag after generated protocol definition
* Default of --objc-strict-protocols is true since this is current
  behaviour

Test have been done manual.
---
 docs/cli-usage.md                         | 265 +++++++++++-----------
 src/main/scala/djinni/Main.scala          |   8 +
 src/main/scala/djinni/ObjcGenerator.scala |  11 +-
 src/main/scala/djinni/generator.scala     |   1 +
 4 files changed, 151 insertions(+), 134 deletions(-)

diff --git a/docs/cli-usage.md b/docs/cli-usage.md
index ef5e9dba..b05d5bbf 100644
--- a/docs/cli-usage.md
+++ b/docs/cli-usage.md
@@ -38,128 +38,129 @@ djinni \
 
 ### General
 
-| Argument | Description |
-| -------- | ----------- |
-| `--help` | Print help  |
-| `--version` | Print version |
-| `--idl <in-file>` | The IDL file with the type definitions, typically with extension `.djinni`. |
+| Argument                        | Description                                                                                          |
+|---------------------------------|------------------------------------------------------------------------------------------------------|
+| `--help`                        | Print help                                                                                           |
+| `--version`                     | Print version                                                                                        |
+| `--idl <in-file>`               | The IDL file with the type definitions, typically with extension `.djinni`.                          |
 | `--idl-include-path <path> ...` | An include path to search for Djinni `@import` and `@extern` directives. Can specify multiple paths. |
 
 ### Java
 
-| Argument | Description |
-| -------- | ----------- |
-| `--java-out <out-folder>` | The output for the Java files (Generator disabled if unspecified). |
-| `--java-package ...` | The package name to use for generated Java classes. |
-| `--java-class-access-modifier <public/package>` | The access modifier to use for generated Java classes (default: `public`). |
-| `--java-cpp-exception <exception-class>` | The type for translated C++ exceptions in Java (default: `java.lang.RuntimeException` that is not checked) |
-| `--java-annotation <annotation-class>` | Java annotation (`@Foo`) to place on all generated Java classes |
-| `--java-generate-interfaces <true/false>` | Whether Java interfaces should be used instead of abstract classes where possible (default: `false`). |
-| `--java-nullable-annotation <nullable-annotation-class>` | Java annotation (`@Nullable`) to place on all fields and return values that are optional |
-| `--java-nonnull-annotation <nonnull-annotation-class>` | Java annotation (`@Nonnull`) to place on all fields and return values that are not optional |
-| `--java-implement-android-os-parcelable <true/false>` | all generated java classes will implement the interface `android.os.Parcelable` |
-| `--java-use-final-for-record <use-final-for-record>` | Whether generated Java classes for records should be marked `final` (default: `true`). |
+| Argument                                                 | Description                                                                                                |
+|----------------------------------------------------------|------------------------------------------------------------------------------------------------------------|
+| `--java-out <out-folder>`                                | The output for the Java files (Generator disabled if unspecified).                                         |
+| `--java-package ...`                                     | The package name to use for generated Java classes.                                                        |
+| `--java-class-access-modifier <public/package>`          | The access modifier to use for generated Java classes (default: `public`).                                 |
+| `--java-cpp-exception <exception-class>`                 | The type for translated C++ exceptions in Java (default: `java.lang.RuntimeException` that is not checked) |
+| `--java-annotation <annotation-class>`                   | Java annotation (`@Foo`) to place on all generated Java classes                                            |
+| `--java-generate-interfaces <true/false>`                | Whether Java interfaces should be used instead of abstract classes where possible (default: `false`).      |
+| `--java-nullable-annotation <nullable-annotation-class>` | Java annotation (`@Nullable`) to place on all fields and return values that are optional                   |
+| `--java-nonnull-annotation <nonnull-annotation-class>`   | Java annotation (`@Nonnull`) to place on all fields and return values that are not optional                |
+| `--java-implement-android-os-parcelable <true/false>`    | all generated java classes will implement the interface `android.os.Parcelable`                            |
+| `--java-use-final-for-record <use-final-for-record>`     | Whether generated Java classes for records should be marked `final` (default: `true`).                     |
 
 ### C++
 
-| Argument | Description |
-| -------- | ----------- |
-| `--cpp-out <out-folder>` | The output folder for C++ files (Generator disabled if unspecified). |
-| `--cpp-header-out <out-folder>` | The output folder for C++ header files (default: the same as `--cpp-out`). |
-| `--cpp-include-prefix <prefix>` | The prefix for `#includes` of header files from C++ files. |
-| `--cpp-namespace ...` | The namespace name to use for generated C++ classes. |
-| `--cpp-ext <ext>` | The filename extension for C++ files (default: `cpp`). |
-| `--hpp-ext <ext>` | The filename extension for C++ header files (default: `hpp`). |
-| `--cpp-optional-template <template>` | The template to use for optional values (default: `std::optional`) |
-| `--cpp-optional-header <header>` | The header to use for optional values (default: `<optional>`) |
-| `--cpp-enum-hash-workaround <true/false>` | Work around LWG-2148 by generating `std::hash` specializations for C++ enums (default: `true`) |
-| `--cpp-nn-header <header>` | The header to use for non-nullable pointers |
-| `--cpp-nn-type <header>` | The type to use for non-nullable pointers (as a substitute for `std::shared_ptr`) |
-| `--cpp-nn-check-expression <header>` | The expression to use for building non-nullable pointers |
-| `--cpp-use-wide-strings <true/false>` | Use wide strings in C++ code (default: `false`) |
-| `--cpp-omit-default-record-constructor <true/false>` | Omit the default constructor for records in C++ code (default: `false`) |
-| `--cpp-json-serialization <nlohmann_json>` | If specified, generate serializers to/from JSON and C++ types using [nlohmann/json](https://github.com/nlohmann/json).|
+| Argument                                             | Description                                                                                                            |
+|------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------|
+| `--cpp-out <out-folder>`                             | The output folder for C++ files (Generator disabled if unspecified).                                                   |
+| `--cpp-header-out <out-folder>`                      | The output folder for C++ header files (default: the same as `--cpp-out`).                                             |
+| `--cpp-include-prefix <prefix>`                      | The prefix for `#includes` of header files from C++ files.                                                             |
+| `--cpp-namespace ...`                                | The namespace name to use for generated C++ classes.                                                                   |
+| `--cpp-ext <ext>`                                    | The filename extension for C++ files (default: `cpp`).                                                                 |
+| `--hpp-ext <ext>`                                    | The filename extension for C++ header files (default: `hpp`).                                                          |
+| `--cpp-optional-template <template>`                 | The template to use for optional values (default: `std::optional`)                                                     |
+| `--cpp-optional-header <header>`                     | The header to use for optional values (default: `<optional>`)                                                          |
+| `--cpp-enum-hash-workaround <true/false>`            | Work around LWG-2148 by generating `std::hash` specializations for C++ enums (default: `true`)                         |
+| `--cpp-nn-header <header>`                           | The header to use for non-nullable pointers                                                                            |
+| `--cpp-nn-type <header>`                             | The type to use for non-nullable pointers (as a substitute for `std::shared_ptr`)                                      |
+| `--cpp-nn-check-expression <header>`                 | The expression to use for building non-nullable pointers                                                               |
+| `--cpp-use-wide-strings <true/false>`                | Use wide strings in C++ code (default: `false`)                                                                        |
+| `--cpp-omit-default-record-constructor <true/false>` | Omit the default constructor for records in C++ code (default: `false`)                                                |
+| `--cpp-json-serialization <nlohmann_json>`           | If specified, generate serializers to/from JSON and C++ types using [nlohmann/json](https://github.com/nlohmann/json). |
 
 ### JNI
 
-| Argument | Description |
-| -------- | ----------- |
-| `--jni-out <out-folder>` | The folder for the JNI C++ output files (Generator disabled if unspecified). |
-| `--jni-header-out <out-folder>` | The folder for the JNI C++ header files (default: the same as `--jni-out`). |
-| `--jni-include-prefix <prefix>` | The prefix for `#includes` of JNI header files from JNI C++ files. |
-| `--jni-include-cpp-prefix <prefix>` | The prefix for `#includes` of the main header files from JNI C++ files. |
-| `--jni-namespace ...` | The namespace name to use for generated JNI C++ classes. |
-| `--jni-generate-main <true/false>` | Generate a source file (`djinni_jni_main.cpp`) that includes the default `JNI_OnLoad` & `JNI_OnUnload` implementation from the support library. (default: `true`) |
+| Argument                            | Description                                                                                                                                                       |
+|-------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `--jni-out <out-folder>`            | The folder for the JNI C++ output files (Generator disabled if unspecified).                                                                                      |
+| `--jni-header-out <out-folder>`     | The folder for the JNI C++ header files (default: the same as `--jni-out`).                                                                                       |
+| `--jni-include-prefix <prefix>`     | The prefix for `#includes` of JNI header files from JNI C++ files.                                                                                                |
+| `--jni-include-cpp-prefix <prefix>` | The prefix for `#includes` of the main header files from JNI C++ files.                                                                                           |
+| `--jni-namespace ...`               | The namespace name to use for generated JNI C++ classes.                                                                                                          |
+| `--jni-generate-main <true/false>`  | Generate a source file (`djinni_jni_main.cpp`) that includes the default `JNI_OnLoad` & `JNI_OnUnload` implementation from the support library. (default: `true`) |
 
 ### Objective-C
 
-| Argument | Description |
-| -------- | ----------- |
-| `--objc-out <out-folder>` | The output folder for Objective-C files (Generator disabled if unspecified). |
-| `--objc-header-out <out-folder>` | The output folder for Objective-C header files (default: the same as `--objc-out`). |
-| `--objc-h-ext <ext>` | The filename extension for Objective-C[++] header files (default: `h`) |
-| `--objc-type-prefix <pre>` | The prefix for Objective-C data types (usually two or three letters) |
-| `--objc-include-prefix <prefix>` | The prefix for `#import` of header files from Objective-C files. |
-| `--objc-swift-bridging-header <name>` | The name of Objective-C Bridging Header used in XCode's Swift projects. The output folder is `--objc-header-out`. |
-| `--objc-closed-enums <true/false>` | All generated Objective-C enums will be `NS_CLOSED_ENUM` (default: `false`). |
+| Argument                               | Description                                                                                                       |
+|----------------------------------------|-------------------------------------------------------------------------------------------------------------------|
+| `--objc-out <out-folder>`              | The output folder for Objective-C files (Generator disabled if unspecified).                                      |
+| `--objc-header-out <out-folder>`       | The output folder for Objective-C header files (default: the same as `--objc-out`).                               |
+| `--objc-h-ext <ext>`                   | The filename extension for Objective-C[++] header files (default: `h`)                                            |
+| `--objc-type-prefix <pre>`             | The prefix for Objective-C data types (usually two or three letters)                                              |
+| `--objc-include-prefix <prefix>`       | The prefix for `#import` of header files from Objective-C files.                                                  |
+| `--objc-swift-bridging-header <name>`  | The name of Objective-C Bridging Header used in XCode's Swift projects. The output folder is `--objc-header-out`. |
+| `--objc-closed-enums <true/false>`     | All generated Objective-C enums will be `NS_CLOSED_ENUM` (default: `false`).                                      |
+| `--objc-strict-protocols <true/false>` | All generated @protocol will implement <NSObject> (default: true).                                                |
 
 ### Objective-C++
 
-| Argument | Description |
-| -------- | ----------- |
-| `--objcpp-out <out-folder>` | The output folder for private Objective-C++ files (Generator disabled if unspecified). |
-| `--objcpp-header-out <out-folder>` | The folder for the Objective-C++ header files (default: the same as `--objcpp-out`). |
-| `--objcpp-ext <ext>` | The filename extension for Objective-C++ files (default: `mm`) |
-| `--objcpp-include-prefix <prefix>` | The prefix for `#import` of Objective-C++ header files from Objective-C++ files. |
-| `--objcpp-include-cpp-prefix <prefix>` | The prefix for `#include` of the main C++ header files from Objective-C++ files. |
-| `--objcpp-include-objc-prefix <prefix>` | The prefix for `#import` of the Objective-C header files from Objective-C++ files (default: the same as `--objcpp-include-prefix`) |
-| `--cpp-extended-record-include-prefix <prefix>` | The prefix path for `#include` of the extended record C++ header (`.hpp`) files |
-|`--objc-extended-record-include-prefix <prefix>` | The prefix path for `#import` of the extended record Objective-C header (`.h`) files  |
-|`--objcpp-namespace <prefix>` | The namespace name to use for generated Objective-C++ classes.  |
+| Argument                                         | Description                                                                                                                        |
+|--------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------|
+| `--objcpp-out <out-folder>`                      | The output folder for private Objective-C++ files (Generator disabled if unspecified).                                             |
+| `--objcpp-header-out <out-folder>`               | The folder for the Objective-C++ header files (default: the same as `--objcpp-out`).                                               |
+| `--objcpp-ext <ext>`                             | The filename extension for Objective-C++ files (default: `mm`)                                                                     |
+| `--objcpp-include-prefix <prefix>`               | The prefix for `#import` of Objective-C++ header files from Objective-C++ files.                                                   |
+| `--objcpp-include-cpp-prefix <prefix>`           | The prefix for `#include` of the main C++ header files from Objective-C++ files.                                                   |
+| `--objcpp-include-objc-prefix <prefix>`          | The prefix for `#import` of the Objective-C header files from Objective-C++ files (default: the same as `--objcpp-include-prefix`) |
+| `--cpp-extended-record-include-prefix <prefix>`  | The prefix path for `#include` of the extended record C++ header (`.hpp`) files                                                    |
+| `--objc-extended-record-include-prefix <prefix>` | The prefix path for `#import` of the extended record Objective-C header (`.h`) files                                               |
+| `--objcpp-namespace <prefix>`                    | The namespace name to use for generated Objective-C++ classes.                                                                     |
 
 ### Python
 
-| Argument | Description |
-| -------- | ----------- |
-| `--py-out <out-folder>` | The output folder for Python files (Generator disabled if unspecified). |
-| `--pycffi-out <out-folder>` | The output folder for PyCFFI files (Generator disabled if unspecified). |
-| `--pycffi-package-name ...`  | The package name to use for the generated PyCFFI classes. |
-| `--pycffi-dynamic-lib-list ...` | The names of the dynamic libraries to be linked with PyCFFI. |
-| `--py-import-prefix <import-prefix>` | The import prefix used within python generated files (default: "") |
+| Argument                             | Description                                                             |
+|--------------------------------------|-------------------------------------------------------------------------|
+| `--py-out <out-folder>`              | The output folder for Python files (Generator disabled if unspecified). |
+| `--pycffi-out <out-folder>`          | The output folder for PyCFFI files (Generator disabled if unspecified). |
+| `--pycffi-package-name ...`          | The package name to use for the generated PyCFFI classes.               |
+| `--pycffi-dynamic-lib-list ...`      | The names of the dynamic libraries to be linked with PyCFFI.            |
+| `--py-import-prefix <import-prefix>` | The import prefix used within python generated files (default: "")      |
 
 ### C wrapper
 
-| Argument | Description |
-| -------- | ----------- |
-| `--c-wrapper-out <out-folder>` |  The output folder for C wrapper files (Generator disabled if unspecified). |
-| `--c-wrapper-header-out <out-folder>` | The output folder for C wrapper header files (default: the same as `--c-wrapper-out`). |
-| `--c-wrapper-include-prefix <prefix>` | The prefix for #includes of C wrapper header files from C wrapper C++ files. |
-| `--c-wrapper-include-cpp-prefix <prefix>` | The prefix for #includes of C++ header files from C wrapper C++ files. |
+| Argument                                  | Description                                                                            |
+|-------------------------------------------|----------------------------------------------------------------------------------------|
+| `--c-wrapper-out <out-folder>`            | The output folder for C wrapper files (Generator disabled if unspecified).             |
+| `--c-wrapper-header-out <out-folder>`     | The output folder for C wrapper header files (default: the same as `--c-wrapper-out`). |
+| `--c-wrapper-include-prefix <prefix>`     | The prefix for #includes of C wrapper header files from C wrapper C++ files.           |
+| `--c-wrapper-include-cpp-prefix <prefix>` | The prefix for #includes of C++ header files from C wrapper C++ files.                 |
 
 ### C++/CLI
 
-| Argument | Description |
-| -------- | ----------- |
-| `--cppcli-out <out-folder>` | The output folder for C++/CLI files (Generator disabled if unspecified). |
-| `--cppcli-namespace ...`    | The namespace name to use for generated C++/CLI classes. |
+| Argument                               | Description                                                                |
+|----------------------------------------|----------------------------------------------------------------------------|
+| `--cppcli-out <out-folder>`            | The output folder for C++/CLI files (Generator disabled if unspecified).   |
+| `--cppcli-namespace ...`               | The namespace name to use for generated C++/CLI classes.                   |
 | `--cppcli-include-cpp-prefix <prefix>` | The prefix for `#include` of the main C++ header files from C++/CLI files. |
 
 
 ### Yaml Generation
 
-| Argument | Description |
-| -------- | ----------- |
-|`--yaml-out <out-folder>` | The output folder for YAML files (Generator disabled if unspecified).  |
-|`--yaml-out-file <out-file>` | If specified all types are merged into a single YAML file instead of generating one file per type (relative to `--yaml-out`).  |
-|`--yaml-prefix <pre>` | The prefix to add to type names stored in YAML files (default: "").  |
+| Argument                     | Description                                                                                                                   |
+|------------------------------|-------------------------------------------------------------------------------------------------------------------------------|
+| `--yaml-out <out-folder>`    | The output folder for YAML files (Generator disabled if unspecified).                                                         |
+| `--yaml-out-file <out-file>` | If specified all types are merged into a single YAML file instead of generating one file per type (relative to `--yaml-out`). |
+| `--yaml-prefix <pre>`        | The prefix to add to type names stored in YAML files (default: "").                                                           |
 
 ### Other
 
-| Argument | Description |
-| -------- | ----------- |
-|`--list-in-files <list-in-files>` | Optional file in which to write the list of input files parsed.  |
-| `--list-out-files <list-out-files>` | Optional file in which to write the list of output files produced.  |
-| `--skip-generation <true/false>` | Way of specifying if file generation should be skipped (default: `false`)  |
+| Argument                            | Description                                                               |
+|-------------------------------------|---------------------------------------------------------------------------|
+| `--list-in-files <list-in-files>`   | Optional file in which to write the list of input files parsed.           |
+| `--list-out-files <list-out-files>` | Optional file in which to write the list of output files produced.        |
+| `--skip-generation <true/false>`    | Way of specifying if file generation should be skipped (default: `false`) |
 
 ### Identifier Style
 
@@ -170,64 +171,64 @@ Possible values: `FooBar`, `fooBar`, `foo_bar`, `FOO_BAR`, `m_fooBar`.
 
 #### C++
 
-| Argument | Default  |
-| -------- | -------- |
-| `--ident-cpp-enum` | `FOO_BAR` |
-| `--ident-cpp-field` | `foo_bar` |
-| `--ident-cpp-method` | `foo_bar` |
-| `--ident-cpp-type` | `FooBar` |
-| `--ident-cpp-enum-type` | `FooBar` |
-| `--ident-cpp-type-param` | `FooBar` |
-| `--ident-cpp-local` | `foo_bar` |
-| `--ident-cpp-file` | `foo_bar` |
+| Argument                 | Default   |
+|--------------------------|-----------|
+| `--ident-cpp-enum`       | `FOO_BAR` |
+| `--ident-cpp-field`      | `foo_bar` |
+| `--ident-cpp-method`     | `foo_bar` |
+| `--ident-cpp-type`       | `FooBar`  |
+| `--ident-cpp-enum-type`  | `FooBar`  |
+| `--ident-cpp-type-param` | `FooBar`  |
+| `--ident-cpp-local`      | `foo_bar` |
+| `--ident-cpp-file`       | `foo_bar` |
 
 #### Java
 
-| Argument | Default  |
-| -------- | -------- |
-| `--ident-java-enum` | `FOO_BAR` |
-| `--ident-java-field` | `fooBar` |
-| `--ident-java-type` | `FooBar` |
-| `--ident-jni-class` | `FooBar` |
-| `--ident-jni-file` | `foo_bar` |
+| Argument             | Default   |
+|----------------------|-----------|
+| `--ident-java-enum`  | `FOO_BAR` |
+| `--ident-java-field` | `fooBar`  |
+| `--ident-java-type`  | `FooBar`  |
+| `--ident-jni-class`  | `FooBar`  |
+| `--ident-jni-file`   | `foo_bar` |
 
 #### Objective C
 
-| Argument | Default  |
-| -------- | -------- |
-| `--ident-objc-enum` | `FooBar` |
-| `--ident-objc-field` | `fooBar` |
-| `--ident-objc-method` | `fooBar` |
-| `--ident-objc-type` | `FooBar` |
+| Argument                  | Default  |
+|---------------------------|----------|
+| `--ident-objc-enum`       | `FooBar` |
+| `--ident-objc-field`      | `fooBar` |
+| `--ident-objc-method`     | `fooBar` |
+| `--ident-objc-type`       | `FooBar` |
 | `--ident-objc-type-param` | `FooBar` |
-| `--ident-objc-local` | `fooBar` |
-| `--ident-objc-file` | `FooBar` |
+| `--ident-objc-local`      | `fooBar` |
+| `--ident-objc-file`       | `FooBar` |
 
 #### Python
 
-| Argument | Default      |
-| -------- | -------- |
-| `--ident-py-type` | `foo_bar` |
-| `--ident-py-class-name` | `FooBar` |
+| Argument                | Default   |
+|-------------------------|-----------|
+| `--ident-py-type`       | `foo_bar` |
+| `--ident-py-class-name` | `FooBar`  |
 | `--ident-py-type-param` | `foo_bar` |
-| `--ident-py-method` | `foo_bar` |
-| `--ident-py-field` | `foo_bar` |
-| `--ident-py-local` | `foo_bar` |
-| `--ident-py-enum` | `Foo_Bar` |
-| `--ident-py-const` | `FOO_BAR` |
+| `--ident-py-method`     | `foo_bar` |
+| `--ident-py-field`      | `foo_bar` |
+| `--ident-py-local`      | `foo_bar` |
+| `--ident-py-enum`       | `Foo_Bar` |
+| `--ident-py-const`      | `FOO_BAR` |
 
 #### C++/CLI
 
-| Argument | Default  |
-| -------- | -------- |
-| `--ident-cppcli-type` | `FooBar` |
+| Argument                    | Default  |
+|-----------------------------|----------|
+| `--ident-cppcli-type`       | `FooBar` |
 | `--ident-cppcli-type-param` | `FooBar` |
-| `--ident-cppcli-property` | `FooBar` |
-| `--ident-cppcli-method` | `FooBar` |
-| `--ident-cppcli-local` | `fooBar` |
-| `--ident-cppcli-enum` | `FooBar` |
-| `--ident-cppcli-const` | `FooBar` |
-| `--ident-cppcli-file` | `FooBar` |
+| `--ident-cppcli-property`   | `FooBar` |
+| `--ident-cppcli-method`     | `FooBar` |
+| `--ident-cppcli-local`      | `fooBar` |
+| `--ident-cppcli-enum`       | `FooBar` |
+| `--ident-cppcli-const`      | `FooBar` |
+| `--ident-cppcli-file`       | `FooBar` |
 
 Example:
 
diff --git a/src/main/scala/djinni/Main.scala b/src/main/scala/djinni/Main.scala
index 6fd7bc4f..7b603e2f 100644
--- a/src/main/scala/djinni/Main.scala
+++ b/src/main/scala/djinni/Main.scala
@@ -86,6 +86,7 @@ object Main {
     var objcppIncludeCppPrefix: String = ""
     var objcppIncludeObjcPrefixOptional: Option[String] = None
     var objcFileIdentStyleOptional: Option[IdentConverter] = None
+    var objcStrictProtocol: Boolean = true
     var objcppNamespace: String = "djinni_generated"
     var cppCliOutFolder: Option[File] = None
     var cppCliIdentStyle = IdentStyle.csDefault
@@ -375,6 +376,12 @@ object Main {
         .text(
           "All generated Objective-C enums will be NS_CLOSED_ENUM (default: false). "
         )
+      opt[Boolean]("objc-strict-protocols")
+        .valueName("<true/false>")
+        .foreach(x => objcStrictProtocol = x)
+        .text(
+          "All generated @protocol will implement <NSObject> (default: true). "
+        )
 
       note("\nObjective-C++")
       opt[File]("objcpp-out")
@@ -916,6 +923,7 @@ object Main {
       cppCliIncludeCppPrefix,
       objcSwiftBridgingHeaderName,
       objcClosedEnums,
+      objcStrictProtocol,
       outFileListWriter,
       skipGeneration,
       yamlOutFolder,
diff --git a/src/main/scala/djinni/ObjcGenerator.scala b/src/main/scala/djinni/ObjcGenerator.scala
index 5fadcb9d..ac367762 100644
--- a/src/main/scala/djinni/ObjcGenerator.scala
+++ b/src/main/scala/djinni/ObjcGenerator.scala
@@ -137,8 +137,15 @@ class ObjcGenerator(spec: Spec) extends BaseObjcGenerator(spec) {
         }
         w.wl
         writeDoc(w, doc)
-        if (i.ext.objc) w.wl(s"@protocol $self <NSObject>")
-        else w.wl(s"@interface $self : NSObject")
+        if (i.ext.objc) {
+          if (spec.objcStrictProtocol) {
+            w.wl(s"@protocol $self <NSObject>")
+          } else {
+            w.wl(s"@protocol $self")
+          }
+        } else {
+          w.wl(s"@interface $self : NSObject")
+        }
         for (m <- i.methods) {
           w.wl
           writeMethodDoc(w, m, idObjc.local)
diff --git a/src/main/scala/djinni/generator.scala b/src/main/scala/djinni/generator.scala
index c9307708..1cc53899 100644
--- a/src/main/scala/djinni/generator.scala
+++ b/src/main/scala/djinni/generator.scala
@@ -86,6 +86,7 @@ package object generatorTools {
       cppCliIncludeCppPrefix: String,
       objcSwiftBridgingHeaderName: Option[String],
       objcClosedEnums: Boolean,
+      objcStrictProtocol: Boolean,
       outFileListWriter: Option[Writer],
       skipGeneration: Boolean,
       yamlOutFolder: Option[File],