add error popup at MarketPassViewController

@@ -243,6 +243,25 @@ import AVFoundation
         spinner.view.removeFromSuperview()
         spinner.removeFromParent()
     }
+
+    func showDialog(_ alertTitle: String, _ alertSubTitle: String) -> Void {
+
+        let alert = UIAlertController(title: alertTitle, message: alertSubTitle, preferredStyle: .alert)
+        alert.addAction(UIAlertAction(title: "OK", style: .default, handler: { action in
+            switch action.style{
+                case .default:
+                print("default")
+
+                case .cancel:
+                print("cancel")
+
+                case .destructive:
+                print("destructive")
+
+            }
+        }))
+        self.present(alert, animated: true, completion: nil)
+    }
     
     func constructBarcode() -> String? {
         // EAN 13 barcode construction
@@ -287,6 +306,7 @@ import AVFoundation
         swiftApi().getMarketPassDetailsAsync(getMarketPassDetailsCallback, failureCallback: {errorCode in
             print("========= getMarketPassDetailsRequest ERROR CODE =========", errorCode)
             self.hideSpinner()
+            self.showDialog("Αποτυχία","Κάτι πήγε στραβά")
         })
     }
 
@@ -301,6 +321,7 @@ import AVFoundation
                 }
             }
         } else {
+            self.showDialog("Αποτυχία","Κάτι πήγε στραβά")
         }
     }
     // MARK: - API Functions