show how to properly ignore invalid ssl certificates while leaving other authentication challenges untouuched

ignoreInvalidSSL

        //setup a new task 
        let configuration = NSURLSessionConfiguration.ephemeralSessionConfiguration()
        let session = NSURLSession(configuration: configuration, delegate: self, delegateQueue: NSOperationQueue.mainQueue())
        let task = session.dataTaskWithURL(url, completionHandler: handleUrlCompleted)
        task.resume()

....

    //url session needs to accept invalid certificates
    func URLSession(session: NSURLSession, didReceiveChallenge challenge: NSURLAuthenticationChallenge, completionHandler: (NSURLSessionAuthChallengeDisposition, NSURLCredential?) -> Void) {
        if(challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust) {
            completionHandler(NSURLSessionAuthChallengeDisposition.UseCredential, NSURLCredential(forTrust: challenge.protectionSpace.serverTrust!))
        }
        else {
            completionHandler(NSURLSessionAuthChallengeDisposition.PerformDefaultHandling, nil)
        }
    }