NSKeyValueBinding.cs

//
// NSKeyValueBinding.cs
//
// Author:
//   Aaron Bockover <abock@xamarin.com>
//
// Copyright 2016 Microsoft. All rights reserved.

using System;
using System.Runtime.InteropServices;

using Foundation;
using ObjCRuntime;

namespace AppKit
{
	static class NSKeyValueBinding
	{
		[DllImport (Constants.ObjectiveCLibrary, EntryPoint = "objc_msgSend")]
		static extern void void_objc_msgSend_IntPtr_IntPtr_IntPtr_IntPtr (
			IntPtr handle, IntPtr sel, IntPtr binding, IntPtr observable, IntPtr keyPath, IntPtr options);

		static readonly IntPtr bindToObjectWithKeyPathOptionsSel = Selector.GetHandle (
			"bind:toObject:withKeyPath:options:");

		public static void Bind (
			this NSObject obj,
			NSString binding,
			NSObject observable,
			string keyPath,
			NSDictionary options = null)
		{
			if (obj == null)
				throw new ArgumentNullException (nameof (obj));

			if (binding == null)
				throw new ArgumentNullException (nameof (binding));

			if (observable == null)
				throw new ArgumentNullException (nameof (observable));

			if (keyPath == null)
				throw new ArgumentNullException (nameof (keyPath));

			var keyPathNative = NSString.CreateNative (keyPath);

			try {
				void_objc_msgSend_IntPtr_IntPtr_IntPtr_IntPtr (
					obj.Handle,
					bindToObjectWithKeyPathOptionsSel,
					binding.Handle,
					observable.Handle,
					keyPathNative,
					options == null ? IntPtr.Zero : options.Handle);
			} finally {
				NSString.ReleaseNative (keyPathNative);
			}
		}

		public static readonly NSString SelectedIndexBinding = Dlfcn.GetStringConstant (
			Dlfcn.dlopen (Constants.AppKitLibrary, 0),
			"NSSelectedIndexBinding");
	}
}