solve core data conflict caused by updating password entity image

pass/Controllers/PasswordDetailTableViewController.swift

@@ -178,7 +178,9 @@ class PasswordDetailTableViewController: UITableViewController, UIGestureRecogni
                     self?.passwordImage = image
                     self?.tableView.reloadRows(at: [indexPath], with: UITableViewRowAnimation.automatic)
                     let imageData = UIImageJPEGRepresentation(image, 1)
-                    self?.passwordEntity?.setValue(imageData, forKey: "image")
+                    if let entity = self?.passwordEntity {
+                        PasswordStore.shared.updateImage(passwordEntity: entity, image: imageData)
+                    }
                 case .failure(let error):
                     print(error)
                 }

pass/Models/PasswordStore.swift

@@ -364,6 +364,29 @@ class PasswordStore {
         }
     }
     
+    func updateImage(passwordEntity: PasswordEntity, image: Data?) {
+        if image == nil {
+            return
+        }
+        let privateMOC = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
+        privateMOC.parent = context
+        privateMOC.perform {
+            passwordEntity.image = NSData(data: image!)
+            do {
+                try privateMOC.save()
+                self.context.performAndWait {
+                    do {
+                        try self.context.save()
+                    } catch {
+                        fatalError("Failure to save context: \(error)")
+                    }
+                }
+            } catch {
+                fatalError("Failure to save context: \(error)")
+            }
+        }
+    }
+    
     func erase() {
         Utils.removeFileIfExists(at: storeURL)
         Utils.removeFileIfExists(at: tempStoreURL)