NSURLErrorDomain Issues

I am trying to setup my development environment to build my first iOS app and I am running into problems when trying to execute a REST call from within my app. The call is being made to a endpoint service (Java Springboot App) that is using a self-signed certificate (created by OpenSSL) that utilizes JWT tokens that is running on my localhost (port 8443).

Here's the specific error I am getting:

domain: "NSURLErrorDomain" - code: 18446744073709550414 0x00007fca19c9e3b0

Here's what I have done to troubleshoot:

• I have set the "NSAppTransportSecurity" in my info.plist file
• I disabled SSL on my endpoint service and then tried to execute the request and everything worked fine (so it seems to just be related to my SSL request)
• Using Postman I am able to successfully retrieve data from the SSL endpoint
• I loaded the SSL cert into a profile in the iOS simulator that I am using (it has the green check "Verified")

Here's my code:

func obtainState() {
     let postEndpoint: String = "https://localhost:8443/api/state"
     let url = NSURL(string: postEndpoint)!
     let session = NSURLSession.sharedSession()
     let request = NSMutableURLRequest(URL: url)
     request.HTTPMethod = "GET"
     request.setValue("eyJhbGciOiJIUzI1NiJ9.eyJ....", forHTTPHeaderField: "Authorization")


     session.dataTaskWithRequest(request, completionHandler: { ( data: NSData?, response: NSURLResponse?, error: NSError?) -> Void in
          guard let realResponse = response as? NSHTTPURLResponse where
          realResponse.statusCode == 200 else {
                    print("Not a 200 response")
                    return
          }
          if let postString = NSString(data:data!, encoding: NSUTF8StringEncoding) as? String {
                print("POST: " + postString)
          }        
        }).resume()
    }

Questions:

• Why am getting this error and what can I do to get past it?
• With iOS 9 can I use self-signed certificates? Will my app be releasable to the AppStore if endusers can configure their own self-signed certs to use in my app?
• Is there an issue using "localhost" in local development with the Simulator?

Thanks for any help you can provide.