let operation = CKModifyRecordsOperation(recordsToSave: largeRecords, recordIDsToDelete: nil)
operation.longLived = true
operation.longLivedOperationWasPersistedBlock = {
    print("Operation with ID", operation.operationID, "was persisted")
}
operation.modifyRecordsCompletionBlock = { (savedRecords, _, error) in
    print("Operation with ID", operation.operationID, "saved records", savedRecords, "error", error)
}
CKContainer.defaultContainer().publicCloudDatabase.addOperation(operation)