查询系统字段时出现CKError：拒绝了“未知字段'createdAt'”

Question

我正在createdAt像这样对系统字段进行排序：

query.sortDescriptors = [NSSortDescriptor(key: "createdAt", ascending: false)]

并得到以下错误：

CKError 0x1c4447fb0：“无效的参数”（12/2018）; 服务器消息=“未知字段'createdAt'”；uuid = 9C450848-2449-4892-93BC-C46363203042; 容器ID =“ ...

我可以查询和排序以这种方式创建的字段。与系统字段有什么不同？该字段的索引是可排序和可查询的。

Answer 1

使用creationDate键。CK仪表板中的元键与用于查询的键略有不同。这是一个元键列表：

recordID: CKRecordID
The unique ID of the record.

recordType: String
The app-defined string that identifies the type of the record.

creationDate: Date?
The time when the record was first saved to the server.

creatorUserRecordID: CKRecordID?
The ID of the user who created the record.

modificationDate: Date?
The time when the record was last saved to the server.

lastModifiedUserRecordID: CKRecordID?
The ID of the user who last modified the record.

recordChangeTag: String?
A string containing the server change token for the record.