Swift核心数据:如何获取数组中的所有项?

我要删除NSManagedObjects天气和当前的现有内容。

let entityNames = ["Weather", "Currently"]
for entityName in entityNames {
    let fetchRequest = NSFetchRequest(entityName: entityName)
    let objects = try(context.execute(fetchRequest)) as? [NSManagedObject]
    for object in objects! {
        context.deletedObjects(object)
    }
}

但是,使用此代码,我在第3行得到一个错误,说明:

未能推断泛型参数“resultType”