Objective-C with Tolc

In order for C++ to be called from Objective-C there has to be an interface level. Tolc generates this level from your already written C++ interface. This is then generated to the appropriate targets by the CMake plugin.


  • MacOS (uses Foundation headers)

Using a C++ library from Objective-C

This is a quick guide to using a C++ library (here called MyLib) from Objective-C. We will:

  1. Download Tolc
  2. Use Tolc to generate bindings to an existing library
  3. Use the C++ library from both Objective-C

The following works on all supported platforms. On all platforms you need git available in your path. Commands that should be run from a terminal starts with $, while comments starts with #.

Downloading and using Tolc

Just add the following in a CMakeLists.txt below where the library you intend to use is defined:

# Download Tolc
# Can be [latest, v0.7.0, ...]
set(tolc_version latest)
  URL https://github.com/Tolc-Software/tolc/releases/download/${tolc_version}/tolc-${CMAKE_HOST_SYSTEM_NAME}.tar.xz

set(tolc_DIR ${tolc_entry_SOURCE_DIR}/lib/cmake/tolc)

  OUTPUT objc-bindings

Assuming your library is called MyLib, and the bindings should be generated to the directory objc-bindings. This will also create a build target as MyLib_objc that you can treat as any other target.

Now you can configure your project as normal (in Visual Studio, this is typically done automatically on save):

$ cmake -S. -Bbuild

And finally build it:

$ cmake --build build

This will produce an Objective-C library under build/tolc (with MSVC it will be under for example build/tolc/Debug).

In order to use it we create an Objective-C application and link it to our libraries:

add_executable(Objecty objc/main.m)
target_link_libraries(Objecty PRIVATE MyLib_objc)

The Tolc CMake plugin has created targets that take care of the rest.

From Objective-C:

#import <Mylib.h>

int main() {
  MyLibMyCppClass* myCppClass = [[MyLibMyCppClass alloc] init];
  [myCppClass someMethod];

If you want to see what more is supported you can take a look at the Examples section.