Declaring self-referencing pointers in Swift [duplicate]

Question

This question already has an answer here:

• Adding observer for KVO without pointers using Swift 5 answers

What would be the equivalent in swift of this Obj-C code?

I'm guessing something with CMutableVoidPointer

static void *CapturingStillImageContext = &CapturingStillImageContext;

Answer 1

Probably something like this:

var CapturingStillImageContext: COpaquePointer = nil
withUnsafePointer(&CapturingStillImageContext) {
    CapturingStillImageContext = COpaquePointer($0) }

Answer 2

CMutableVoidPointer isn't available anymore as of Beta 3. Theres UnsafePointer and ConstUnsafePointer - you can declare it this way:

let CapturingStillImageContext = UnsafePointer<()>()

Answer 3

I've been using this technique, but it would be nice to find a more elegant solution:

var SelfReferencingKey = initialize_SelfReferencingKey()

func initialize_SelfReferencingKey() -> UnsafePointer<()> {
    return withUnsafePointer(&SelfReferencingKey, { UnsafePointer($0) } )
}