joulupukki / btcloudkitsync Goto Github PK

Originally the sync was arranged serially and there would be a begin sync, sync messages, and an end sync. Now that the code has changed around, fix up the sync notifications so the UI can display proper sync messages if desired.

I believe that all that needs to happen is:

1. Save the server change token
2. Call performSync: recursively? (or maybe instrument another CKFetchRecordsOperation)

While uploading records, CloudKit may respond with CKErrorLimitExceeded to indicate that the request to the server is too large. According to the WWDC video on CloudKit (I think the Tips & Tricks video), the number of records should be chopped in half and sent again to the server.

From CKError.h:

Saving a record would exceed quota

Describe registering for silent push notifications, how to implement the BTCloudKitSyncDatabase protocol, and strategies for implementing a local cache (database).

If the developer changes the BTCloudKitSyncDatabase implementation and provides a different recordZoneName, we'll want to delete any old subscriptions because the implementation appends "Subscription" to the recordZoneName.

From CKError.h:

One of the items in this batch operation failed in a zone with atomic updates, so the entire batch was rejected.

Most of the main errors are already documented in other issues, but there are many errors declated in CKError.h:

• CKErrorInternalError - CloudKit.framework encountered an error. This is a non-recoverable error.
• CKErrorPartialFailure - Some items failed, but the operation succeeded overall
• CKErrorNetworkUnavailable - Network not available
• CKErrorNetworkFailure - Network error (available but CFNetwork gave us an error)
• CKErrorBadContainer - Un-provisioned or unauthorized container. Try provisioning the container before retrying the operation.
• CKErrorServiceUnavailable - Service unavailable
• CKErrorRequestRateLimited - Client is being rate limited
• CKErrorMissingEntitlement - Missing entitlement
• CKErrorNotAuthenticated - Not authenticated (writing without being logged in, no user record)
• CKErrorPermissionFailure - Access failure (save or fetch)
• CKErrorUnknownItem - Record does not exist
• CKErrorInvalidArguments - Bad client request (bad record graph, malformed predicate)
• CKErrorResultsTruncated - Query results were truncated by the server
• CKErrorServerRecordChanged - The record was rejected because the version on the server was different
• CKErrorServerRejectedRequest - The server rejected this request. This is a non-recoverable error
• CKErrorAssetFileNotFound - Asset file was not found
• CKErrorAssetFileModified - Asset file content was modified while being saved
• CKErrorIncompatibleVersion - App version is less than the minimum allowed version
• CKErrorConstraintViolation - The server rejected the request because there was a conflict with a unique field.
• CKErrorOperationCancelled - A CKOperation was explicitly cancelled
• CKErrorChangeTokenExpired - The previousServerChangeToken value is too old and the client must re-sync from scratch
• CKErrorBatchRequestFailed - One of the items in this batch operation failed in a zone with atomic updates, so the entire batch was rejected.
• CKErrorZoneBusy - The server is too busy to handle this zone operation. Try the operation again in a few seconds.
• CKErrorBadDatabase - Operation could not be completed on the given database. Likely caused by attempting to modify zones in the public database.
• CKErrorQuotaExceeded - Saving a record would exceed quota
• CKErrorZoneNotFound - The specified zone does not exist on the server
• CKErrorLimitExceeded - The request to the server was too large. Retry this request as a smaller batch.
• CKErrorUserDeletedZone - The user deleted this zone through the settings UI. Your client should either remove its local data or prompt the user before attempting to re-upload any data to this zone.

Hi any info on why we should use this over CloudKit iCloud Core Data? Thanks.

If the developer changes the BTCloudKitSyncDatabase implementation and provides a different recordZoneName, we'll want to delete any old zones.

• Check for CKErrorServerRecordChanged and figure out what the best policy is for changes. Should client always win? Use the keys here to get the records involved in the conflict: https://developer.apple.com/library/ios/documentation/CloudKit/Reference/CloudKit_constants/index.html#//apple_ref/doc/constant_group/Record_Changed_Error_Keys
• Figure out how to resend the resolved items. I think you use CKRecordChangedErrorServerRecordKey (the CKRecord that currently exists on the server), make any field changes to it, save the changes locally to match, and then push these changes to the server. The trick is how to instrument this as part of the initial push of local changes

BTCloudKitSync does not yet handle conflict resolution. Need to determine a good policy for how to deal with this. Should server or client changes "win" in a conflict. Part of dealing with this is also figuring out how to deal with the NSOperation that's currently pushing changes and re-sending the conflicted records.

Hi,

This looks like a great project. Just what I was looking for. However, how does it handle CKAsset and CKReference objects?

I need to be able to store a variable amount of attachments on a record and I thought maybe creating multiple child CKRecords and using CKReference to link them back to the parent CKRecord might be a way of doing that, each related record having its own CKAsset object on it.

Is there any planned support for that?

Looking at the code I wonder if it would be better to allow the delegate to provide the CKRecord objects to sync rather than providing an array of NSDictionary objects? If it was that way, then I could provide an array of CKRecord objects which already had their relationships to other CKRecord objects established and already populated with their CKAsset fields.

Thanks,

Brendan