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A bridge between an Objective C runtime environment and Python.

Project Description


Rubicon-ObjC is a bridge between Objective-C and Python. It enables you to:

  • Use Python to instantiate objects defined in Objective-C,
  • Use Python to invoke methods on objects defined in Objective-C, and
  • Subclass and extend Objective-C classes in Python.

It also includes wrappers of the some key data types from the Foundation framework (e.g., NSString).


Rubicon uses a combination of ctypes, plus Objective-C’s own reflection APIs, to enable Objective-C objects to be referenced in a Python process.

To install Rubicon, use pip:

$ pip install rubicon-objc

Then, in a Python shell

>>> from ctypes import cdll
>>> from ctypes import util
>>> from rubicon.objc import ObjCClass, NSObject, objc_method

# Use ctypes to import a framework into the Python process
>>> cdll.LoadLibrary(util.find_library("Foundation"))

# Wrap an Objective-C class contained in the framework
>>> NSURL = ObjCClass("NSURL")

# Then instantiate the Objective-C class, using the API
# that is exposed through Objective-C. The Python method name
# is the Objective-C method descriptor, up to the first colon.
# The first argument (if it exists) is passed in as is; subsequent
# arguments are passed in as keyword arguments. Properties can be
# accessed and modified directly. So, the equivalent of:
# NSURL *base = [NSURL URLWithString:@""];
# NSURL *full = [NSURL URLWithString:@"contributing/" relativeToURL:base];
# NSLog(@"absoluteURL = %@", [full absoluteURL]);
# would be:
>>> base = NSURL.URLWithString("")
>>> full = NSURL.URLWithString("", relativeToURL=base)
>>> print("absoluteURL = %s" % full.absoluteURL)

# Sometimes, a method will use have the same keyword argument name twice.
# This is legal in Objective-C, but not in Python; in this case, you can
# explicitly name a descriptor by replacing colons with underscores:
>>> base = NSURL.URLWithString_("")
>>> full = NSURL.URLWithString_relativeToURL_("", base)
>>> print("absoluteURL = %s" % full.absoluteURL)

# To create a new Objective-C class, define a Python class that
# has the methods you want to define, decorate it to indicate that it
# should be exposed to the Objective-C runtime, and annotate it to
# describe the type of any arguments that aren't of type ``id``:
>>> class Handler(NSObject):
...     @objc_method
...     def initWithValue_(self, v: int):
...         self.value = v
...         return self
...     @objc_method
...     def pokeWithValue_(self, v: int) -> None:
...         print("Poking with", v)
...         print("Internal value is", self.value)

# Then use the class:
>>> my_handler = Handler.alloc().initWithValue_(42)
>>> my_handler.pokeWithValue_(37)


To run the Rubicon test suite:

  1. Compile the Rubicon test library. A Makefile has been provided to make this easy. Type:

    $ make

    to compile it.

    Cross platform support

    This Makefile currently only works under OS X; however, the build commands aren’t complicated; it should be fairly easy to reproduce the build on other platforms. Pull requests to make the Makefile cross-platform are welcome.

  2. Put the Rubicon support library somewhere that it will be found by dynamic library discovery. This means:

    1. Under OS X, put the tests/objc directory in your DYLD_LIBRARY_PATH
    2. Under Linux, put the tests/objc directory in your LD_LIBRARY_PATH
    3. Under Windows… something :-)
  3. Run the test suite:

    $ python test

    A tox configuration has also been provided; to run the tests across all supported platforms, run:

    $ tox


Rubicon is part of the BeeWare suite. You can talk to the community through:

We foster a welcoming and respectful community as described in our BeeWare Community Code of Conduct.


If you experience problems with this backend, log them on GitHub. If you want to contribute code, please fork the code and submit a pull request.

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File Name & Checksum SHA256 Checksum Help Version File Type Upload Date
rubicon_objc-0.2.8-py3-none-any.whl (32.0 kB) Copy SHA256 Checksum SHA256 py3 Wheel Aug 14, 2017
rubicon-objc-0.2.8.tar.gz (43.1 kB) Copy SHA256 Checksum SHA256 Source Aug 14, 2017

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