CKRecord.ID
An object that uniquely identifies a record in a database.
Declaration
class IDOverview
A record ID object consists of a name string and a zone ID. The name string is an ASCII string that doesn’t exceed 255 characters in length. When you create a record without specifying a record ID, the ID name string derives from a UUID and is, therefore, unique. When creating your own record ID objects, you can use names that have more meaning to your app or to the user, as long as each name is unique within the specified zone. For example, you might use a document name for the name string.
CloudKit uniques records by recordID within a specified database, but you can reuse record IDs in different databases. Each container has a public and a private database, and the private database is different for each unique user. This configuration provides for the reusing of record IDs in each user’s private database, but ensures that only one record uses a specific record ID in the public database.
CloudKit generally creates record IDs when it first saves a new record, but you might manually instantiate instances of CKRecordID in specific situations. For example, you must create an instance when saving a record in a zone other than the default zone. You also instantiate instances of CKRecordID when retrieving specific records from a database.
Don’t subclass CKRecordID.
Interacting with Record IDs
After you create a CKRecordID object, interactions with that object typically involve creating a new record or retrieving an existing record from a database.
You might also use record IDs when you can’t use a CKRecord.Reference object to refer to a record. References are only valid within a single zone of a database. To refer to objects outside of the current zone or database, save the strings in the record’s CKRecordID and CKRecordZone.ID objects. When you want to retrieve the record later, use those strings to recreate the record and zone ID objects so that you can fetch the record.
Creating Record IDs for New Records
To assign a custom record ID to a new record, you must create the CKRecordID object first. You need to know the intended name and zone information for that record, which might also require creating a CKRecordZone.ID object. After creating the record ID object, initialize your new record using its init(recordType:recordID:) method.
Using Record IDs to Fetch Records
Use a record ID to fetch the corresponding CKRecord object from a database quickly. You perform the fetch operation using a CKFetchRecordsOperation object or the fetch(withRecordID:completionHandler:) method of the CKDatabase class. In both cases, CloudKit returns the record asynchronously using the handler you provide.