Sign up / Login in swift 2.0 Error - swift

Question

Not quite sure what i'm missing here to make this code work. Trying to make an app with login / sign up connecting to a server but i cant seem to get it to work. This is my code :
do {
let post:NSString = "username=\(username)&password=\(password)"
NSLog("PostData: %#",post)
let url:NSURL = NSURL(string: "http://www.ec2-54-191-63-219.us-west-2.compute.amazonaws.com/userRegistration.php")!
let postData:NSData = post.dataUsingEncoding(NSUTF8StringEncoding)!
let request:NSMutableURLRequest = NSMutableURLRequest(URL: url)
request.HTTPMethod = "POST"
request.HTTPBody = postData
let task = NSURLSession.sharedSession().dataTaskWithRequest(request)
{data, response, error in
do {
let json = try NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers ) as? NSDictionary
if let parsejson = json
{
let resultValue:String = parsejson["status"] as! String
print("result: \(resultValue)")
if (resultValue == "Success")
{
let alert = UIAlertController(title: "Success", message: "Registration Successful", preferredStyle: UIAlertControllerStyle.Alert)
let okAction = UIAlertAction(title: "Ok", style: UIAlertActionStyle.Default){action in self.dismissViewControllerAnimated(true, completion: nil)}
alert.addAction(okAction)
self.presentViewController(alert, animated: true, completion: nil)
}
else
{
print(resultValue)
}
}
} catch {
print("failed: \(error)")
}
}
task.resume()
this is the error i get when i try and add an account:
PostData: username=Optional("josh")&password=Optional("test")
fatal error: unexpectedly found nil while unwrapping an Optional value

Answer 1

The error message says it all, you are derefencing a nil data value, likely data in the line JSONObjectWithData(data!, ..., but it should be obvious from where the debugger stops. guard against the error, and go upstream from that.
if error != nil { handle error and abort }
... etc