Ios 获取的结果控制器在controllerDidChangeContent之后复制结果

我有两张桌子：一张是所有员工的名单，另一张是能够提供某种服务（即按摩）的员工名单

数据模型如下所示：

每项服务都可以有许多员工提供，每个员工都可以提供许多服务（多对多关系）。 问题是，每次我将员工从

员工列表

拖放到提供此服务的

员工

时，当我从最后一个索引开始时，会得到重复的结果，而当我从第一个索引开始时，一切正常

当我再次加载viewController时（即使没有再次启动应用程序），所有数据都会正确显示。 此处代码：
在

EmployeesAvailableTableViewController.swift中

I初始化

NSFetchedResultsController

func initializeFetchedResultsController() {
     let appDelegate = UIApplication.shared.delegate as! AppDelegate
     let context = appDelegate.managedObjectContext
     let request: NSFetchRequest<Employee>
     request = NSFetchRequest(entityName: "Employee")
     //this predicate show only those employee who don't have the entity `service` yet.
     request.predicate = NSPredicate(format: "SUBQUERY(service, $c, $c.service_id == %@).@count == 0", (service?.service_id!)!)

     let lastNameSort = NSSortDescriptor(key: "lastName", ascending: true)
            request.sortDescriptors = [lastNameSort]

     fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)

     fetchedResultsController?.delegate = self

      do {
           //I added this as suggested in another question on stackoverflow but nothing has changed
           if (self.fetchedResultsController?.fetchedObjects == nil){

                try fetchedResultsController?.performFetch()

            }
        } catch {
            fatalError("Failed to initialize FetchedResultsController: \(error)")
        }
}

func initializeFetchedResultsController() {
        let appDelegate = UIApplication.shared.delegate as! AppDelegate
        let context = appDelegate.managedObjectContext
        context.stalenessInterval = 0
        let request: NSFetchRequest<Employee>

        request = NSFetchRequest(entityName: "Employee")
        request.predicate = NSPredicate(format: "ANY service.service_id == %@", (service?.service_id)!)

        let lastNameSort = NSSortDescriptor(key: "lastName", ascending: true)
        request.sortDescriptors = [lastNameSort]


        fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
        fetchedResultsController?.delegate = self

        do {

            if (self.fetchedResultsController?.fetchedObjects == nil)
            {

                try fetchedResultsController?.performFetch()

            }
        } catch {
            fatalError("Failed to initialize FetchedResultsController: \(error)")
        }

}
   //both this delegates methods get called 

func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
self.assignedEmployeeTableView.reloadData()
}

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
self.assignedEmployeeTableView.reloadData()
}

最后，在

PriceListViewController

func initializeFetchedResultsController() {
     let appDelegate = UIApplication.shared.delegate as! AppDelegate
     let context = appDelegate.managedObjectContext
     let request: NSFetchRequest<Employee>
     request = NSFetchRequest(entityName: "Employee")
     //this predicate show only those employee who don't have the entity `service` yet.
     request.predicate = NSPredicate(format: "SUBQUERY(service, $c, $c.service_id == %@).@count == 0", (service?.service_id!)!)

     let lastNameSort = NSSortDescriptor(key: "lastName", ascending: true)
            request.sortDescriptors = [lastNameSort]

     fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)

     fetchedResultsController?.delegate = self

      do {
           //I added this as suggested in another question on stackoverflow but nothing has changed
           if (self.fetchedResultsController?.fetchedObjects == nil){

                try fetchedResultsController?.performFetch()

            }
        } catch {
            fatalError("Failed to initialize FetchedResultsController: \(error)")
        }
}

func initializeFetchedResultsController() {
        let appDelegate = UIApplication.shared.delegate as! AppDelegate
        let context = appDelegate.managedObjectContext
        context.stalenessInterval = 0
        let request: NSFetchRequest<Employee>

        request = NSFetchRequest(entityName: "Employee")
        request.predicate = NSPredicate(format: "ANY service.service_id == %@", (service?.service_id)!)

        let lastNameSort = NSSortDescriptor(key: "lastName", ascending: true)
        request.sortDescriptors = [lastNameSort]


        fetchedResultsController = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
        fetchedResultsController?.delegate = self

        do {

            if (self.fetchedResultsController?.fetchedObjects == nil)
            {

                try fetchedResultsController?.performFetch()

            }
        } catch {
            fatalError("Failed to initialize FetchedResultsController: \(error)")
        }

}
   //both this delegates methods get called 

func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
self.assignedEmployeeTableView.reloadData()
}

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
self.assignedEmployeeTableView.reloadData()
}

func initializeFetchedResultsController（）{
让appDelegate=UIApplication.shared.delegate为！appDelegate
让上下文=appDelegate.managedObjectContext
context.stalenessInterval=0
let请求：NSFetchRequest
request=NSFetchRequest（entityName:“雇员”）
request.predicate=NSPredicate（格式：“ANY service.service\u id==%@”，（service？.service\u id）！）
让lastNameSort=NSSortDescriptor（键：“lastName”，升序：true）
request.sortDescriptors=[lastNameSort]
fetchedResultsController=NSFetchedResultsController（fetchRequest:request，managedObjectContext:context，sectionNameKeyPath:nil，cacheName:nil）
fetchedResultsController？.delegate=self
做{
if（self.fetchedResultsController？.fetchedObject==nil）
{
请尝试获取ResultsController？.performFetch（）
}
}抓住{
fatalError（“未能初始化FetchedResultsController:\（错误）”）
}
}
//这两个委托方法都会被调用
func controllerWillChangeContent（\ucontroller:NSFetchedResultsController）{
self.assignedEmployeeTableView.reloadData（）
}
func controllerDidChangeContent（\控制器：NSFetchedResultsController）{
self.assignedEmployeeTableView.reloadData（）
}