# `PyObjCTools.Conversion` – Convert data structures

Functions for converting between Cocoa and pure Python data structures.

PyObjCTools.Conversion.propertyListFromPythonCollection(pyCol, conversionHelper=None)

  Convert a Python collection (dictionary, array, tuple, string) into an Objective-C collection.

  If conversionHelper is defined, it must be a callable. It will be called for any object encountered for which `propertyListFromPythonCollection()` cannot automatically convert the object. The supplied helper function should convert the object and return the converted form. If the conversion helper cannot convert the type, it should raise an exception or return None.

PyObjCTools.Conversion.pythonCollectionFromPropertyList(ocCol, conversionHelper=None)

  Converts a Foundation based collection– a property list– into a Python collection. Like `propertyListFromPythonCollection()`, `conversionHelper` is an optional callable that will be invoked any time an encountered object cannot be converted.