PointerIssue.swift

import Cocoa
import AVFoundation
import CoreAudio

// The Weak struct is the weak wrapper
struct Weak<T: AnyObject> {
    weak var object: T?
}

// TestObject represents the AudioPlayer class
class TestObject {
    let value = "test"
    
    init () {
        // This is where you would set up the audio and get a working AUGraph that can generate notifications
        var graph: AUGraph?
        NewAUGraph(&graph)
        
        // Create a wrapper for this object
        var weakWrapper = Weak<TestObject>()
        weakWrapper.object = self

        // Create the wrapper pointer
        let size = MemoryLayout<Weak<TestObject>>.size
        let weakWrapperPointer = UnsafeMutableRawPointer.allocate(byteCount: size, alignment: 1)
        weakWrapperPointer.storeBytes(of: weakWrapper, as: Weak<TestObject>.self)
        
        // This is the problem. I can't figure out how to get this to work without crashing
        AUGraphAddRenderNotify(graph!, { (rawPointer, _, _, _, _, _) -> OSStatus in
            let weakWrapperPointer = rawPointer.assumingMemoryBound(to: Weak<TestObject>.self)
            let weakWrapper = weakWrapperPointer.pointee
            if let object = weakWrapper.object {
                print(object.value)
            }
            
            return noErr
        }, weakWrapperPointer)
    }
}


// Create a test object (represents the AudioPlayer)
var testObject: TestObject? = TestObject()

// Remove test object from memory after 3 seconds
DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
    testObject = nil
}