Using NSUrlProtocol to add a custom header

I have an app where I need to add a custom request header for all outgoing requests from UIWebView. I believe the way to accomplish this is to use a custom NSUrlProtocol.

My example below is "working" but has issues, and I'm not quite sure what they are to be honest. I'm getting some intermittent loading issues where sometimes a WebView will load but other times it will not. I'm not sure if this is a garbage collection issue or not, but I can't seem to pin anything down. It seems to happen on devices and not the debugger, so I can't really track down what is happening as well.

I'm not sure if all of what I'm doing in my example is necessary. I only need to add the header...if there is a more simple way to accomplish this, please let me know.

Thanks!

public class MyCustomUrlProtocol : NSUrlProtocol
{
    private NSUrlConnection connection;
    private MyCustomConnectionDelegate connDelegate;

    [Export ("canInitWithRequest:")]
    public static bool canInitWithRequest (NSUrlRequest request)
    {
        if (null != request.Headers && request.Headers.ContainsKey (NSObject.FromObject ("MyCustomHeader"))) {
            return false; // request has already been handled
        }
        return true;
    }

    [Export ("canonicalRequestForRequest:")]
    public static new NSUrlRequest GetCanonicalRequest (NSUrlRequest request)
    {
        return request;
    }

    [Export ("initWithRequest:cachedResponse:client:")]
    public MyCustomUrlProtocol (NSUrlRequest request, NSCachedUrlResponse cachedResponse, NSUrlProtocolClient client) 
        : base (request, cachedResponse, client)
    {
    }

    public override void StartLoading ()
    {
        if (null == connDelegate) {
            connDelegate = new MyCustomConnectionDelegate (this);
        }
        // inject the ]HTTP header
        NSMutableDictionary headers = new NSMutableDictionary (Request.Headers);
        headers.Add(NSObject.FromObject("MyCustomHeader"), NSObject.FromObject ("MyCustomValue"));
        NSMutableUrlRequest newRequest = (NSMutableUrlRequest)Request.MutableCopy ();
        newRequest.Headers = headers;

        this.connection = new NSUrlConnection (newRequest, connDelegate, true);
    }

    public override void StopLoading ()
    {
        if (this.connection != null) {
            this.connection.Cancel ();
            this.connection = null;
        }
    }

    protected override void Dispose (bool disposing)
    {
        StopLoading ();
    }

    private class MyCustomConnectionDelegate : NSUrlConnectionDelegate
    {
        private MyCustomUrlProtocol handler;

        public MyCustomConnectionDelegate (MyCustomUrlProtocol handler) {
            this.handler = handler;
        }
        public override void ReceivedData (NSUrlConnection connection, NSData data)
        {
            handler.Client.DataLoaded (handler, data);
        }
        public override void FailedWithError (NSUrlConnection connection, NSError error)
        {
            handler.Client.FailedWithError (handler, error);
            handler.StopLoading ();
        }
        public override void ReceivedResponse (NSUrlConnection connection, NSUrlResponse response)
        {
            handler.Client.ReceivedResponse (handler, response, NSUrlCacheStoragePolicy.NotAllowed);
        }
        public override void FinishedLoading (NSUrlConnection connection)
        {
            handler.Client.FinishedLoading (handler);
            handler.StopLoading ();
        }
        protected override void Dispose (bool disposing)
        {
            handler.StopLoading ();
        }
    }
}