Post Notification using Apple NSNotificationCenter with Pure c# and CoreFoundation

AppleMessageSend.cs

#nullable enable
using System;
using System.Runtime.InteropServices;
using System.Text;

public static class AppleMessagesend
{

#if UNITY_IOS || UNITY_EDITOR_OSX || UNITY_STANDALONE_OSX || UNITY_TVOS

    private const uint kCFStringEncodingUTF8 = 0x08000100;

    [DllImport("__Internal", CharSet = CharSet.Ansi)]
    private static extern IntPtr CFStringCreateWithCString(
        IntPtr alloc,
        [MarshalAs(UnmanagedType.LPUTF8Str)] string cStr,
        uint encoding
    );

    [DllImport("__Internal")]
    private static extern void CFRelease(IntPtr cf);

    [DllImport("__Internal")]
    private static extern void CFRetain(IntPtr cf);

    [DllImport("__Internal")]
    private static extern IntPtr CFDataCreate(IntPtr allocator, byte[] bytes, nint length);

    [DllImport("__Internal")]
    private static extern void CFShow(IntPtr cfRef);

    [DllImport("__Internal")]
    private static extern IntPtr CFPropertyListCreateWithData(
        IntPtr allocator,
        IntPtr data,
        ulong options,
        IntPtr format, // nullable
        out IntPtr error    // nullable
    );

    [DllImport("__Internal")]
    private static extern IntPtr CFNotificationCenterGetLocalCenter();

    [DllImport("__Internal")]
    private static extern void CFNotificationCenterPostNotification(IntPtr center, IntPtr name, IntPtr obj, IntPtr userInfo, bool deliverImmediately);

    [DllImport("__Internal")]
    private static extern ulong CFDictionaryGetTypeID();

    [DllImport("__Internal")]
    private static extern ulong CFGetTypeID(IntPtr cf);

    [DllImport("__Internal")]
    private static extern IntPtr CFCopyDescription(IntPtr cf);

    [DllImport("__Internal", CallingConvention = CallingConvention.Cdecl)]
    private static extern bool CFStringGetCString(
        IntPtr cfString,
        StringBuilder buffer,
        nint maxSize,
        uint encoding
    );

    [DllImport("__Internal")]
    private static extern nint CFStringGetLength(IntPtr cfString);


    [DllImport("__Internal", EntryPoint = "objc_getClass")]
    private static extern IntPtr objc_getClass(string name);

    [DllImport("__Internal", EntryPoint = "sel_registerName")]
    private static extern IntPtr sel_registerName(string name);



    [DllImport("__Internal", EntryPoint = "objc_msgSend")]
    private static extern IntPtr sendDataToJsonMsg(IntPtr NSJSONSerializationClazz, IntPtr selector, IntPtr CFDataRef, nuint JSONReadingOption, out IntPtr error);


    private sealed class CFObject : IDisposable
    {
        public IntPtr Handle { get; private set; }

        private CFObject(IntPtr handle) => Handle = handle;

        public static CFObject? Create(IntPtr handle)
            => handle == IntPtr.Zero ? null : new CFObject(handle);

        public void Dispose()
        {
            if (Handle != IntPtr.Zero)
            {
                CFRelease(Handle);
                Handle = IntPtr.Zero;
            }
        }

        public static implicit operator IntPtr(CFObject? obj) => obj?.Handle ?? IntPtr.Zero;
    }

    private ref struct AutoreleasePool
    {

        [DllImport("__Internal")]
        private static extern IntPtr objc_autoreleasePoolPush();

        [DllImport("__Internal")]
        private static extern void objc_autoreleasePoolPop(IntPtr pool);

        private IntPtr Handle;

        private AutoreleasePool(IntPtr handle)
        {
            Handle = handle;
        }

        public void Dispose()
        {
            if (Handle != IntPtr.Zero)
            {
                objc_autoreleasePoolPop(Handle);
                Handle = IntPtr.Zero;
            }
        }

        public static AutoreleasePool Create()
        {
            IntPtr handle = objc_autoreleasePoolPush();
            if (handle == IntPtr.Zero)
                throw new InvalidOperationException("Failed to create autorelease pool.");
            return new AutoreleasePool(handle);
        }



    }

    private readonly ref struct NSAutoreleasePoolRef
    {

        [DllImport("__Internal", EntryPoint = "objc_msgSend")]
        private static extern void msgSendVoid(IntPtr receiver, IntPtr selector);

        [DllImport("__Internal", EntryPoint = "objc_msgSend")]
        private static extern IntPtr objc_msgSendId(IntPtr receiver, IntPtr selector);

        private readonly IntPtr Handle;

        private NSAutoreleasePoolRef(IntPtr handle)
        {
            Handle = handle;
        }

        public void Dispose()
        {
            if (Handle != IntPtr.Zero)
            {
                IntPtr selector = sel_registerName("drain");
                msgSendVoid(Handle, selector);
            }
        }

        public bool IsValid => Handle != IntPtr.Zero;

        public static NSAutoreleasePoolRef Create()
        {
            IntPtr NSAutoreleasePool = objc_getClass("NSAutoreleasePool");
            if (NSAutoreleasePool == IntPtr.Zero)
            {
                UnityEngine.Debug.LogError("[AppleMessagesend] NSAutoreleasePool class not found.");
                return new NSAutoreleasePoolRef(IntPtr.Zero);
            }
            IntPtr selector = sel_registerName("new");
            IntPtr handle = objc_msgSendId(NSAutoreleasePool, selector);
            if (handle == IntPtr.Zero)
            {
                UnityEngine.Debug.LogError("[AppleMessagesend] Failed to dispatch msg to NSAutoreleasePool.");
                return new NSAutoreleasePoolRef(IntPtr.Zero);
            }
            return new NSAutoreleasePoolRef(handle);
        }



    }


    private static string CFStringToString(IntPtr cfString)
    {

        
        if (cfString == IntPtr.Zero)
            return string.Empty;
        // Get character length (UTF-16 characters)
        nint length = CFStringGetLength(cfString);
        if (length == 0)
            return string.Empty;

        // Worst-case buffer size: 4 bytes per UTF-16 char (very conservative)
        int bufferSize = (int)(length * 4) + 1;
        StringBuilder sb = new(bufferSize);
        if (CFStringGetCString(cfString, sb, sb.Capacity, kCFStringEncodingUTF8))
        {
            return sb.ToString();
        }
        return string.Empty;
    }

    // Recommended to use with  https://github.com/animetrics/PlistCS
    public static bool DispatchMessage(string @namespace, byte[] plistBytes)
    {
        if (string.IsNullOrEmpty(@namespace) || plistBytes.Length == 0)
            return false;
        using var pool = AutoreleasePool.Create();
        using var cfName = CFObject.Create(
            CFStringCreateWithCString(IntPtr.Zero, @namespace, kCFStringEncodingUTF8)
        );
        using var cfData = CFObject.Create(
            CFDataCreate(IntPtr.Zero, plistBytes, plistBytes.Length)
        );
        if (cfName == null || cfData == null)
            return false;
        using var plist = CFObject.Create(
            CFPropertyListCreateWithData(
                IntPtr.Zero,
                cfData,
                0, // options
                IntPtr.Zero, // format
                out IntPtr errorRef // error
            )
        );
        using var error = CFObject.Create(errorRef);
        if (plist == null)
        {
            UnityEngine.Debug.LogWarning("[AppleMessagesend] Failed to parse plist.");
            if (error != null)
            {
                using var cfString = CFObject.Create(CFCopyDescription(error))!;
                var description = CFStringToString(cfString);
                if (!string.IsNullOrEmpty(description))
                {
                    UnityEngine.Debug.LogError(description);
                }
                else
                {
                    CFShow(error);
                }
            }
            return false;
        }
        else if (CFGetTypeID(plist) != CFDictionaryGetTypeID())
        {
            using var cfString = CFObject.Create(CFCopyDescription(plist))!;
            var description = CFStringToString(cfString);
            if (!string.IsNullOrEmpty(description))
            {
                UnityEngine.Debug.LogError("[AppleMessagesend] plist is not a dictionary. => " + description);
            }
            else
            {
                UnityEngine.Debug.LogError("[AppleMessagesend] plist is not a dictionary. with unknown description.");
                CFShow(plist);
            }
            return false;
        }
        else
        {
            using var cfString = CFObject.Create(CFCopyDescription(plist))!;
            var description = CFStringToString(cfString);
            UnityEngine.Debug.Log("[AppleMessagesend] sending " + description);

            IntPtr center = CFNotificationCenterGetLocalCenter();
            CFNotificationCenterPostNotification(center, cfName, IntPtr.Zero, plist, true);
            return true;
        }


    }

    public static bool DispatchJSON(string @namespace, byte[] jsonBytes)
    {
        if (string.IsNullOrEmpty(@namespace) || jsonBytes.Length == 0)
            return false;
        using var pool = NSAutoreleasePoolRef.Create();
        if (!pool.IsValid)
        {
            UnityEngine.Debug.LogError("[AppleMessagesend] Failed to create NSAutoreleasePool.");
            return false;
        }
        using var cfName = CFObject.Create(
            CFStringCreateWithCString(IntPtr.Zero, @namespace, kCFStringEncodingUTF8)
        );
        using var cfData = CFObject.Create(
            CFDataCreate(IntPtr.Zero, jsonBytes, jsonBytes.Length)
        );
        if (cfName == null || cfData == null)
            return false;

        IntPtr NSJSONSerializationClazz = objc_getClass("NSJSONSerialization");
        IntPtr selector = sel_registerName("JSONObjectWithData:options:error:");
        IntPtr errorRef = IntPtr.Zero;

        var json = CFObject.Create(
            sendDataToJsonMsg(NSJSONSerializationClazz, selector, cfData, 0, out errorRef)
        );
        using var error = CFObject.Create(errorRef);
        if (json == null)
        {
            if (error != null)
            {
                using var cfString = CFObject.Create(CFCopyDescription(error))!;
                var description = CFStringToString(cfString);
                if (!string.IsNullOrEmpty(description))
                {
                    UnityEngine.Debug.LogError("[AppleMessagesend] Failed to parse JSON. error : => " + description);
                }
                else
                {
                    UnityEngine.Debug.LogError("[AppleMessagesend] Failed to parse JSON. with unknown error.");
                    CFShow(error);
                }
            }
            return false;
        }
        else if (CFGetTypeID(json) != CFDictionaryGetTypeID())
        {
            using var cfString = CFObject.Create(CFCopyDescription(json))!;
            var description = CFStringToString(cfString);
            if (!string.IsNullOrEmpty(description))
            {
                UnityEngine.Debug.LogError("[AppleMessagesend] JSON is not a dictionary. => " + description);
            }
            else
            {
                UnityEngine.Debug.LogError("[AppleMessagesend] JSON is not a dictionary. with unknown description.");
                CFShow(json);
            }
            return false;
        }
        else
        {
            using var cfString = CFObject.Create(CFCopyDescription(json))!;
            var description = CFStringToString(cfString);
            UnityEngine.Debug.Log("[AppleMessagesend] sending " + description);

            IntPtr center = CFNotificationCenterGetLocalCenter();
            CFNotificationCenterPostNotification(center, cfName, IntPtr.Zero, json, true);
            return true;
        }

    }

#else

    public static bool DispatchMessage(string @namespace, byte[] plistBytes)
    {
        Debug.LogError("[AppleMessagesend] DispatchMessage is not supported on this platform.");
        return false;
    }

    public static bool DispatchJSON(string @namespace, byte[] jsonBytes)
    {
        Debug.LogError("[AppleMessagesend] DispatchJSON is not supported on this platform.");
        return false;
    }
#endif

}