如何确认核心数据执行

Question

我正在尝试确认核心数据中的所有数据是否已通过以下来源删除（其中“CoreDataHelper.getCoreDataHelper().context”为 NSManagedObjectContext）

public static func delete(predicates: [NSPredicate] = []) {
    let fetchRequest = request(predicates: predicates)
    let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
    do {
        let result1 = try CoreDataHelper.getCoreDataHelper().context.fetch(fetchRequest)
        NSLog("Delete batch size: %d", result1.count)
        let result2 = try CoreDataHelper.getCoreDataHelper().context.execute(deleteRequest)
        NSLog("Delete request succeeded: %d", result2)
    } catch {
        NSLog("Delete request failed")
        return
    }
}

当我测试它时，日志中会显示以下内容

删除批量大小：1

删除请求成功：250432

但是当我真正看到数据时，它似乎并没有被删除。 我尝试添加数据，因为发生数据已在核心数据中的错误。

public static func add(from object: Dictionary<String, Any>) -> NSManagedObjectProtocol? {
    let exists = fetch(id: object)
    if exists.count > 0 {
        NSLog("Object already exists in CoreData : %@", object.description)
        return nil
    } else {
        return newObject(object: object) as NSManagedObjectProtocol
    }
}

对象已存在于 CoreData 中： ....

所以我的问题是我如何知道 NSBatchDeleteRequest 的执行功能正常工作。有没有返回值可以用来确认执行是否没有错误？

Answer 1

删除后保存您的NSManagedContext：

public static func delete(predicates: [NSPredicate] = []) {
    let fetchRequest = request(predicates: predicates)
    let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest)
    do {
        ...
        let result2 = try CoreDataHelper.getCoreDataHelper().context.execute(deleteRequest)
        //save context
        try CoreDataHelper.getCoreDataHelper().context.save()
    } catch {
        NSLog("Delete request failed")
        return
    }
}