Convert NSObjects to .NET primitives

gistfile1.cs

class NSObjectConverter
{
	static IntPtr selObjCType = MonoMac.ObjCRuntime.Selector.GetHandle ("objCType");
	static IntPtr clsNSCFBoolean = Class.GetHandle ("NSCFBoolean");
	
	public static object ConvertNumber (NSNumber num)
	{
		char kind;
		unsafe {
			kind = (char) *((byte *) MonoMac.ObjCRuntime.Messaging.IntPtr_objc_msgSend (num.Handle, selObjCType));
		}
		
		switch (kind) {
		case 'c':
			//HACK: bools always seem to be encoded as char type so inspect the class
			if (num.ClassHandle == clsNSCFBoolean)
				goto case 'B';
			return num.SByteValue;
		case 'C':
			//HACK: bools always seem to be encoded as char type so inspect the class
			if (num.ClassHandle == clsNSCFBoolean)
				goto case 'B';
			return num.ByteValue;
		case 'B':
			return num.BoolValue;
		case 's':
			return num.Int16Value;
		case 'S':
			return num.UInt16Value;
		case 'i':
		case 'l':
			return num.Int32Value;
		case 'I':
		case 'L':
			return num.UInt32Value;
		case 'q':
			return num.Int64Value;
		case 'Q':
			return num.UInt64Value;
		case 'f':
			return num.FloatValue;
		case 'd':
			return num.DoubleValue;
		default:
			throw new NotSupportedException ("NSNumber of type " + kind);
		}
	}
	
	public static byte[] ConvertData (NSData data)
	{
		var bytes = new byte[data.Length];
		Marshal.Copy (data.Bytes, bytes, 0, (int)data.Length);
		return bytes;
	}
	
	public static object ConvertPrimitive (NSObject obj)
	{
		var arr = obj as NSArray;
		if (arr != null) {
			var objArr = new object[arr.Count];
			for (uint i = 0; i < objArr.Length; i++) {
				objArr[i] = ConvertPrimitive (MonoMac.ObjCRuntime.Runtime.GetNSObject (arr.ValueAt (i)));
			}
			return MakeStrongerTypedArray (objArr);
		}
		
		var str = obj as NSString;
		if (str != null)
			return str.ToString ();
		
		var num = obj as NSNumber;
		if (num != null)
			return ConvertNumber (num);
		
		var date = obj as NSDate;
		if (date != null)
			return (DateTime) (NSDate) date;
		
		var data = obj as NSData;
		if (data != null)
			return ConvertData (data);
		
		throw new NotSupportedException (obj.ToString ());
	}

	static Type FindStrongestCommonType (System.Collections.IEnumerable objects)
	{
		var en = objects.GetEnumerator ();
		if (!en.MoveNext ())
			throw new ArgumentException ();
			
		Type t = en.Current.GetType ();
		Type o = typeof (object);
		
		while (en.MoveNext ()) {
			var u = en.Current.GetType ();
			while (!u.IsSubclassOf (t)) {
				t = t.BaseType;
				if (t.Equals (o))
					return o;
			}
		}
		
		return t;
	}
	
	static Array MakeStrongerTypedArray (object[] objArr)
	{
		if (objArr.Length == 0)
			return objArr;
		
		var t = FindStrongestCommonType (objArr);
		if (t.Equals (typeof (object)))
		    return objArr;
		
		var typedArr = Array.CreateInstance (t, objArr.Length);
		Array.Copy (objArr, typedArr, objArr.Length);
			return typedArr;
	}
}