从CoreData获取比较和删除字符串

Question

1. 我想从CoreData中删除自定义单元格中UILabel提供的单个字符串。因此，从表视图中删除一行是行不通的。

2. 此外，我想检查CoreData值中是否有特定的字符串。

例如：

我有一个名为"收藏夹"的实体，其属性名为"服务"，插入的字符串名为"micro"。我想删除"micro"。此外，我想检查"micro"（例如）是否在属性"services"和实体"Favorites"的字符串中。

我试过这个：

1.

let serString = servico.text
        let appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
        let contexto:NSManagedObjectContext = appDel.managedObjectContext
        let entidade = NSEntityDescription.entityForName("Favorites", inManagedObjectContext: contexto)
        let pedido = NSFetchRequest(entityName: "Favorites")
        pedido.predicate = NSPredicate(format: "service = %@", serString!)
        let p:Favorites? = Favorites(entity: entidade!, insertIntoManagedObjectContext: contexto)
            contexto.deleteObject(p!)

但它并没有删除字符串"serString"

2。尝试过这个：

var request : NSFetchRequest = NSFetchRequest(entityName: "Favorites");
    request.predicate = NSPredicate(format: "services = %s", "micro")
    let results : [NSManagedObject] = context.executeFetchRequest(request, error: &error)
    if (results.count > 0) {
        print("exists")        }
    else {
        //Doesn't exist
    }

但在"&error"中给出错误，称"使用未解析的标识符‘error’"

2（b）。

也尝试过这个，但崩溃了应用程序输出给

"打印错误描述：（NSError）error="超出范围"

（lldb）"

let request : NSFetchRequest = NSFetchRequest(entityName:     "Favorites");
    request.predicate = NSPredicate(format: "services = %s", "micro")
do {
let results : [NSManagedObject] = try   context.executeFetchRequest(request) as! [Favorites]
if (results.count > 0) {
            print("exists")        }
        else {
            //Doesn't exist
        }
        // success ...
    } catch let error as NSError {
        // failure
        print("Fetch failed: (error.localizedDescription)")
    }

更新：

1. 这段代码最终删除了字符串：

   let favoriteFetchRequest = NSFetchRequest(entityName:"Favorites")
       let predicate = NSPredicate(format: "services = %@", serv)
       favoriteFetchRequest.predicate = predicate
   do {
      let fetchedEntities = try       context.executeFetchRequest(favoriteFetchRequest) as! [NSManagedObject]
   for entity in fetchedEntities {
   context.deleteObject(entity)
   try context.save()
   }
   } catch let error as NSError {
   print("Fetch failed: (error.localizedDescription)")
   }
   

2号有什么帮助吗？

Answer 1

1。我认为你需要这样的东西：

       contexto.deleteObject(p!)
        do {
            try contexto.save()
            print("Borrado ")
        } catch _ as NSError {
            print( "Error en delete")
        }