Conversion from .net types to obj-c types

Hi all,

I'm writing a helper class which will wrap a native iOS library in Xamarin. One of the native properties I want to reference is of type NSObject, and I would like to get automatic conversion from sensible .net types to objc types where available - i.e. double, int, short etc to NSNumber, DateTime to NSDate etc.

I know that mono will perform the conversion for you if the native type is specified (i.e. the property is of NSNumber type), however as I mentioned the properties I have are of type NSObject.

Am I missing an easy way to do this? At the moment I've written the following extension method on System.Object, which will attempt to convert the types I care about:

public static class NSObjectConversionExtensions
{
    /// <summary>
    /// Attempts to convert native .net types to objC types.
    /// Works for:
    ///  - DateTime
    ///  - String
    ///  - Number types
    /// </summary>
    /// <returns>The objective C representation</returns>
    /// <param name="o">The .net object</param>
    public static NSObject ConvertToNSObject(this object o)
    {
        NSObject toReturn;
        // Specific types first - DateTime
        if (o is DateTime) {
            toReturn = (NSDate)((DateTime)o);
        }
        // Now a String
        else if (o is string) {
            toReturn = (NSString)((string)o);
        }
        // And a catch-all for number types
        else if (typeof(IConvertible).IsAssignableFrom (o.GetType ())) {
            try {
                // Most types will convert happily to a double
                toReturn = (NSNumber)(((IConvertible)o).ToDouble (CultureInfo.InvariantCulture.NumberFormat));
            } catch (InvalidCastException e) {
                throw new InvalidCastException ("Unable to convert from .net type to objC type.", e);
            }
        }
        // We can't do it
        else {
            throw new InvalidCastException ("Unable to convert from .net type to objC type.");
        }

        // Send the result back
        return toReturn;
    }
}

Does anybody have any better suggestions? If not, has anybody else faced this problem? What did you do to solve it?

Much appreciated

sam