[swift-users] C interop: passing null pointers to unwrapped unsafe pointers

Joe Groff jgroff at apple.com
Fri Oct 7 11:25:53 CDT 2016

> On Oct 7, 2016, at 7:02 AM, Ingo Maier via swift-users <swift-users at swift.org> wrote:
> Is there a way in Swift 3 to pass a null pointer to a C function that
> takes an implicitly unwrapped unsafe pointer? I understand that
> pointer parameters in C that don't specify nullability are mapped to
> implicitly unwrapped pointers in Swift 3. Since it's not uncommon for
> existing unannotated C APIs to accept null pointers, I assume there
> has to be a way other than creating my own bridge functions in C. I
> hope I am not wrong.
> I am a bit surprised that I couldn't find an answer to this, neither
> on this list nor on stackoverflow, as I presume I am not the only one
> with this problem. Sorry, if I missed something.

An implicitly unwrapped Optional is still an Optional. You can use `nil` to pass a null pointer.


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