Invoking swift in objective-C++ (.mm file)

Question

Can one invoke Swift code in a Objective-C++ (.mm) file? Are there any simple workarounds if not?

I have a Xcode project that is a mix of Swift, Objective-C and C++. I have no problem going from Objective-C to Swift with the -Bridging-Header.h or from Swift to Objective-C with the -Swift.h.

I do however have a .mm file which is Objective-C++. When I try to #import "[ProductName]-Swift.h" it throws many compile errors in the -Swift.h file such as:

Cannot find protocol declaration for 'NSApplicationDelegate', did you mean 'NSConnectionDelegate'?

No type protocol named 'NSTableViewDataSource'

etc...

I have looked into several other similar questions such as Can I mix Swift with C++? Like the Objective - C .mm files but it does not seem to give me an explicit answer or a solution.

As I see it, my current workaround is to create a wrapper object in Objective-C that uses the Swift code and then import that into the Objective-C++ code.

Maybe the problem has to do with the fact that `@import` statements do not work with Objective-C++? — user102008, Oct 17 '15 at 08:09

score 14 · Accepted Answer · edited Jul 28 '21 at 12:47

14

I just succeeded in compiling a .mm file invoking swift by adding -fcxx-modules flag. The <Module>-Swift.h file generated by Xcode includes @import and checks for modules support. Found out the flag from this answer: https://stackoverflow.com/a/20708695/2570853.

edited Jul 28 '21 at 12:47

Prashant Tukadiya

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answered Dec 15 '15 at 07:23

cahn

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Where do you set the flag? – Simon Bøgh Dec 03 '17 at 23:29
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Double click the file in build phases and enter the flag. – cahn Dec 05 '17 at 06:06

Invoking swift in objective-C++ (.mm file)

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