如何删除Coredata Swift 3中的所有实体对象

Question

所以我有这个代码可以正常，但是我想要一个更好的代码。

func deleteCoreDataObjects() {
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    //where groupData is an Array of an Entity
    for i in 0..<self.groupData.count {
        context.delete(groupData[i])
    }

    (UIApplication.shared.delegate as! AppDelegate).saveContext()
}

目前，我正在通过循环删除对象。

Answer 1

您可以尝试以下方法：

func deleteAllData(entity: String)
{
    let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    let managedContext = appDelegate.managedObjectContext
    let fetchRequest = NSFetchRequest(entityName: entity)
    fetchRequest.returnsObjectsAsFaults = false
    do 
    {
        let results = try managedContext.executeFetchRequest(fetchRequest)
        for managedObject in results
        {
            let managedObjectData:NSManagedObject = managedObject as! NSManagedObject
            managedContext.deleteObject(managedObjectData)
        }
    } catch let error as NSError {
        print("Detele all data in (entity) error : (error) (error.userInfo)")
    }
}

用法：

self.deleteAllData("your_entityName")

已经在：https：//stackoverflow.com/a/33931528/2894160

Answer 2

最好的是删除持久存储，然后添加新的词而不是循环每个实体（如果您想从coredata删除所有实体）。

）。

func deletepersistentStoreCoorDinator（）{

    do {
        let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("YourDatabaseName.sqlite")
        try self.persistentStoreCoordinator.destroyPersistentStoreAtURL(url, withType: NSSQLiteStoreType, options: nil)
        try self.persistentStoreCoordinator.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil)
    }
    catch{
    }
}

Answer 3

这是从核心数据删除记录的代码：//从本地DB

删除用户信息

func deleteUserInfo()  {
    let context = appdelegate.managedObjectContext
    let coord   = appdelegate.persistentStoreCoordinator
    let fetchRequest = NSFetchRequest(entityName: "User")
    if #available(iOS 9.0, *) {
        let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
        //let predicate = NSPredicate(format: "id == %@", key)
        //fetchRequest.predicate = predicate
        do {
            try coord.executeRequest(deleteRequest, withContext: context)
        }
        catch let error as NSError {
            //Error handling
        }
        catch {}
    } else {
        // Fallback on earlier versions
        do {
        let users: NSArray = try appdelegate.managedObjectContext.executeFetchRequest(fetchRequest)
        for user in users {
            appdelegate.managedObjectContext.delete(user)
        }
        try appdelegate.managedObjectContext.save()
        } catch let error as NSError {
            //Error handling
        }
        catch {}
    }
}