查询系统字段时的CKError :拒绝“未知字段'createdAt'”

Question

我对createdAt系统字段进行了如下排序：

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

并得到以下错误：

CKError 0x1c4447fb0：“无效参数”(12/2018)；服务器消息=“未知字段'createdAt'"；uuid =9C450848-2449-2492-93BC-C46363203042；容器ID =”.

我能够以这种方式查询和排序我创建的字段。系统字段有什么不同吗？该字段的索引是可排序的和可查询的。

Answer 1

相反，使用creationDate作为密钥。CK仪表板中的元键与用于查询的略有不同。以下是一个元密钥列表：

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.