[swift-users] Why does withUnsafePointer(to:) require a var argument?

Rick Mann rmann at latencyzero.com
Thu Apr 27 21:31:11 CDT 2017

> On Apr 27, 2017, at 18:56 , Hooman Mehr <hooman at mac.com> wrote:
> You should be able to type your `dataBuffer ` as [Int8] (Byte array). Then you won’t need `withUnsafeMutableBytes`. You can simply call it like this:
> self.request = c_library_call(&params, dataBuffer) // Call as if it is a C array

Hmm. I'm not able to pass self.dataBuffer or self.dataBuffer! to the call. It's expecting `UnsafeMutableRawPointer!`.

> It works because of C interoperability compiler magic.
> As long as the instance holding `dataBuffer` is not deallocated and you have not resized the array, the pointer should remain valid. 

Rick Mann
rmann at latencyzero.com

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