Practice_CFDictionary.swift

import Foundation
import CoreFoundation

// https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFCollections/Articles/creating.html#//apple_ref/doc/uid/20001132-101215-CHDEBBDB

class MyObject: NSObject {
    var string: NSString
    
    init(string: NSString) {
        self.string = string
        super.init()
    }
    
    deinit {
        print("deinit!!!")
    }
    
    override func copy() -> Any {
        MyObject(string: string.copy() as! NSString)
    }
}

let retainCallBack: CFDictionaryRetainCallBack = { allocator, ptr in 
    UnsafeRawPointer(Unmanaged<AnyObject>.passRetained(unsafeBitCast(ptr, to: AnyObject.self)).toOpaque())
}

let releaseCallBack: CFDictionaryReleaseCallBack = { allocator, ptr in
    Unmanaged<AnyObject>.passUnretained(unsafeBitCast(ptr, to: AnyObject.self)).release()
}

let copyDescriptionCallBack: CFDictionaryCopyDescriptionCallBack = { ptr in
    let value: AnyObject = unsafeBitCast(ptr, to: AnyObject.self)
    
    let result: AnyObject = (value.copy?() as? AnyObject) ?? value
    
    let format: CFString = CFStringCreateWithCString(kCFAllocatorDefault, "[%@]", CFStringBuiltInEncodings.UTF8.rawValue)
    let args: [CVarArg] = [UInt(bitPattern: Unmanaged<AnyObject>.passRetained(result).toOpaque())]
    
    let description: CFString = withVaList(args) { p in
        CFStringCreateWithFormatAndArguments(kCFAllocatorDefault, nil, format, p)
    }
    
    return Unmanaged<CFString>.passRetained(description)
}

let equalCallBack: CFDictionaryEqualCallBack = { lhsPtr, rhsPtr in
    let lhsObject: AnyObject = unsafeBitCast(lhsPtr, to: AnyObject.self)
    let rhsObject: AnyObject = unsafeBitCast(rhsPtr, to: AnyObject.self)
    
    return .init(lhsObject.isEqual(rhsObject))
}

let hashCallBack: CFDictionaryHashCallBack = { ptr in
    return .init(unsafeBitCast(ptr, to: AnyObject.self).hash ?? .zero)
}

let valueCallBacks: CFDictionaryValueCallBacks = .init(
    version: .zero,
    retain: retainCallBack,
    release: releaseCallBack,
    copyDescription: copyDescriptionCallBack,
    equal: equalCallBack
)

autoreleasepool { 
    let dictionary: CFMutableDictionary = withUnsafePointer(to: valueCallBacks) { p in
        CFDictionaryCreateMutable(
            kCFAllocatorDefault,
            1,
            nil,
            p
        )
    }
    
    let object: MyObject = .init(string: "Test")

    CFDictionarySetValue(dictionary, .init(bitPattern: 3), Unmanaged<MyObject>.passUnretained(object).toOpaque())
    CFShow(dictionary)
}