Fastest way to get (const) pointer to struct for inter-operability with C/C++

[Martin (Martin R)]

@davidbaraff

I could use withUnsafePointer { }, but this (as far as I can tell) will make a copy
of actual_data.

It does not make a copy, as far as I know. According to the documentation, it

Invokes the given closure with a pointer to the given argument.

Compare also Allow let-to-pointer conversions, where it is said that

@Torust

With the introduction of withUnsafePointer<T>(to: T) , let -bound variables can be converted to UnsafePointer s without creation of temporaries.

Therefore

let result = withUnsafePointer(to: actual_data, { some_c_function($0)} )

should be what you are looking for.