当最小iOS为9.0时，使用NSBatchDeleteRequest删除多条记录。如果是后台线程，执行NSManagedObjectContext save，否则使用NSFetchRequest获取记录并删除for循环中的所有记录，删除完成后保存。

迅捷用户界面

从实体中获取实例，然后循环删除每个实例。

@Environment(\.managedObjectContext) var moc
    
@FetchRequest(sortDescriptors: []) var wizards: FetchedResults<Wizard>

var body: some View {
    VStack {
        List() { }

        Button("Delete all") {
            for wizard in wizards {
                moc.delete(wizard)
            }
            
            if moc.hasChanges {
                try? moc.save()
            }
        }
    }
}

Swift 4, iOS 12和Xcode 10更新

100%工作，只是剪切和粘贴

只要把这个函数放在相关的类中，并在viewDidLoad()或任何地方或在一个函数或按钮下调用这个函数self.deleteData()，这样通过单击一个按钮，所有来自实体的数据都应该被删除，并替换“myEntity”作为你在核心数据中定义的实体

func deleteData() {
    let appDel:AppDelegate = (UIApplication.shared.delegate as! AppDelegate)
    let context:NSManagedObjectContext = appDel.persistentContainer.viewContext
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "myEntity")
    fetchRequest.returnsObjectsAsFaults = false         
    do {
        let results = try context.fetch(fetchRequest)
        for managedObject in results {
            if let managedObjectData: NSManagedObject = managedObject as? NSManagedObject {
                context.delete(managedObjectData)
            }
        }
    } catch let error as NSError {
        print("Deleted all my data in myEntity error : \(error) \(error.userInfo)")
    }
}

为什么不将接收到的数据与现有缓存一起折叠呢?否则它就不是真正的“刷新”，而是“重新开始”，你也可以删除SQLLite文件并重新开始(假设你没有持久化其他数据)。

Swift 4, iOS 10+ 静态函数，可以应用于任何实体删除其所有数据

protocol NSManagedObjectHelper {
}
extension NSManagedObject: NSManagedObjectHelper {
}
extension NSManagedObjectHelper where Self: NSManagedObject {
    static func removeAllObjectsInContext(_ managedContext: NSManagedObjectContext) {
        let request: NSFetchRequest = NSFetchRequest(entityName: String(describing: self))
        let deleteRequest = NSBatchDeleteRequest(fetchRequest: request)
        do {
            deleteRequest.resultType = .resultTypeObjectIDs//to clear objects from memory
            let result = try managedContext.execute(deleteRequest) as? NSBatchDeleteResult
            if let objectIDArray = result?.result as? [NSManagedObjectID] {
                let changes = [NSDeletedObjectsKey : objectIDArray]
                /*By calling mergeChangesFromRemoteContextSave, all of the NSManagedObjectContext instances that are referenced will be notified that the list of entities referenced with the NSManagedObjectID array have been deleted and that the objects in memory are stale. This causes the referenced NSManagedObjectContext instances to remove any objects in memory that are loaded which match the NSManagedObjectID instances in the array.*/
                NSManagedObjectContext.mergeChanges(fromRemoteContextSave: changes, into: [managedContext])
            }
            try managedContext.save()
        } catch let error {
            print(error)
        }
    }
}

“房间”是一个实体

Room.removeAllObjectsInContext(self.persistentContainer.viewContext)

在20191025编辑:如果我们在同一个项目中使用多个目标，"Self.fetchRequest()"指令可能会导致问题。所以替换为NSFetchRequest(entityName: String(description: self))

这段代码适用于iOS 9及以下版本

class func deleteAllRecords(in entity : String) // entity = Your_Entity_Name
    {

        let context = CoreDataStack.getContext() // Note:- Replace your context here with CoreDataStack.getContext()
        let deleteFetch = NSFetchRequest<NSFetchRequestResult>(entityName: entity)
        if #available(iOS 9, *)
        {
            let deleteRequest = NSBatchDeleteRequest(fetchRequest: deleteFetch)
            do
            {
                try context.execute(deleteRequest)
                try context.save()
            }
            catch
            {
                print("There was an error:\(error)")
            }
        }
        else
        {
            do{
                let deleteRequest = try context.fetch(deleteFetch)
                for anItem in deleteRequest {
                    context.delete(anItem as! NSManagedObject)
                }
            }
            catch
            {
                print("There was an error:\(error)")
            }
        }
        CoreDataStack.saveContext() // Note:- Replace your savecontext here with CoreDataStack.saveContext()
    }