Nitpick: Objective-C and C are terrific for interoperation. FFI works pretty well with Obj-C and C too because it is all based on C binary compatibility and predictable symbol mangling. This is how previous Apple language bridges like PyObjC and RubyCocoa worked.
C++ and thus Objective-C++ has always been a disaster for FFI or anything that depends on binary compatibility or predictable symbol name mangling. Obj-C++ has a lot of ugly areas partly because of this. Kudos to Apple to making it work as well as it does.
Swift is terrific that it also seems to interoperate with C/Obj-C nearly seamlessly (bridging headers), but it is no surprise that the Swift documentation immediately says it doesn't support C++ and you must build C interface wrappers.
C++ and thus Objective-C++ has always been a disaster for FFI or anything that depends on binary compatibility or predictable symbol name mangling. Obj-C++ has a lot of ugly areas partly because of this. Kudos to Apple to making it work as well as it does.
Swift is terrific that it also seems to interoperate with C/Obj-C nearly seamlessly (bridging headers), but it is no surprise that the Swift documentation immediately says it doesn't support C++ and you must build C interface wrappers.
* Edit: reclarified comment