current location click then throw error swift

@IBAction func btnCurrentLocationClick(sender: UIButton) { self.zoomToLocation(mapView.userLocation.coordinate, animated: true) SVProgressHUD.showWithStatus("Please wait...", maskType: .Clear) delay(1.0) { print("Hello!") SwiftLocation.shared.reverseCoordinates(Service.GoogleMaps, coordinates: self.centerLocation, onSuccess: { (place) -> Void in SVProgressHUD.dismiss() let placemark:CLPlacemark! = place let dicAddress:NSDictionary! = placemark.addressDictionary let formattedAddress = dicAddress["FormattedAddressLines"] as! NSArray let address = formattedAddress.componentsJoinedByString(", ") let udefault=NSUserDefaults.standardUserDefaults() udefault.setValue(address, forKey: "pDescript") udefault.setDouble(self.centerLocation.latitude, forKey: "leti") udefault.setDouble(self.centerLocation.longitude, forKey: "longi") print(address) }, onFail: { (error) -> Void in alertShowWithToast((error?.localizedDescription)!); SVProgressHUD.dismiss() }) } this is my code...if click current location button. then throw this error. fatal error: unexpectedly found nil while unwrapping an Optional value