Swift : fatal error: unexpectedly found nil while unwrapping an Optional value - ios

Question

I am trying to access REST web service, but its giving this - fatal error: unexpectedly found nil while unwrapping an Optional value.
Below is the code - So i have this RESTParser class -
protocol RESTParserDelegate
{
func getReceiveData(data:NSMutableData,sender:RESTParser)
}
class RESTParser: NSObject, NSURLConnectionDataDelegate
{
var receiveData: NSMutableData!
var requestConnection: NSURLConnection!
var delegate: RESTParserDelegate?
func receiveData(resData:NSMutableData){
receiveData = resData
}
func requestConnection(reqConn:NSURLConnection){
requestConnection = reqConn
}
func httpRequest(myRequest:NSMutableURLRequest){
self.requestConnection = NSURLConnection(request: myRequest, delegate: self)
}
// NSURLConnectionDataDelegate methods
func connection(connection: NSURLConnection, didReceiveData data: NSData){
self.receiveData?.appendData(data)
}
func connectionDidFinishLoading(connection: NSURLConnection){
self.delegate?.getReceiveData(receiveData, sender: self) // error # this line
self.delegate = nil
self.receiveData = nil
self.requestConnection = nil
}
func connection(connection: NSURLConnection, didFailWithError error: NSError){
NSLog("Failed with error - %# ",error.localizedDescription)
}
func parseData(data:NSMutableData){
}
}
Error is # this line - self.delegate?.getReceiveData(receiveData, sender: self) in connectionDidFinishLoading function.
And calling this from my project details view controller - but as soon as getReceiveData method is called this fatal error is coming.
class ProjectDetails_tab: UIViewController, RESTParserDelegate{
override func viewDidLoad() {
super.viewDidLoad();
//var projectData: NSDictionary = [String:String]()
var url:String = "http://domianName.com"
var nsURL = NSURL(string: url)
var createrequest: NSMutableURLRequest = NSMutableURLRequest(URL: nsURL!)
createrequest.HTTPMethod = "GET"
var rest = RESTParser()
rest.delegate=self
rest.httpRequest(createrequest)
}
func getReceiveData(data:NSMutableData,sender:RESTParser){
}
}

Answer 1

Not clear that fatal error with which line of your code. But you can recheck your delegate object or:
// NSURLConnectionDataDelegate methods
func connection(didReceiveResponse: NSURLConnection, didReceiveResponse response: NSURLResponse) {
// Recieved a new request, clear out the data object
self.receiveData = NSMutableData()
}
func connection(connection: NSURLConnection, didReceiveData data: NSData){
self.receiveData?.appendData(data)
}
func connectionDidFinishLoading(connection: NSURLConnection!) {
// Request complete, self.data should now hold the resulting info
}