iCloud sync for iPad

[ShammyLevva]

Given the new proper iPad support in v4, that makes using the iPad to plan caching a pleasure to do, could consideration be given to v4 having an option to sync offline lists to iCloud. It would be great to be able to create a list on one device and have it auto sync to the other.

Obviously this would be an option people could choose between say, don’t sync, manual sync, auto sync. Perhaps with a Wi-fi only auto sync for folks worried about data plan usage. So ideally then 4 options.

I would envisage the auto sync check routine would only kick in to check for updates when you started the app or when you opened the offline list view. A date stamp check on the list data file on iCloud should be sufficient to confirm an updated file. 

This would also mean people’s lists would be backed up when they upgraded devices. Which is a commonly suggested thing people are surprised doesn’t happen. 

[rragan]

My guess is that Cachly offline lists do not exist as separate files as you might imagine. They are stored as data in the unified data base which is why you only have one instance of a cache regardless of the number of offline lists.  Sync would require extracting all the list entries to a file and then sync of that file. The extract process is what happens when you do an Export to GPX. 

I do plan routes on the iPad but when ready to go out, I export the GPX and AirDrop it to Cachly on the iPhone. Not perfect and once in awhile I tweak something and forget to re-export so sync would be nice but I don't see it as easy to do. If I'm Road tripping by car, the iPad comes along and I can AirDrop anytime. 

[ShammyLevva]

I’m not assuming they currently exist as a file. Only that when stored on iCloud they would exist as separate files so that a quick timestamp check would identify changes. 

The logic of the process is very simple if the list doesn’t exist then run the export routine as you describe only without user intervention required. If it does exist then compare date stamps can import export as appropriate if the dates are different. Note the date will be stamped as per iCloud so device independent. 

Really not a terribly difficult process to add as a large part of the logic already exists. In particular the core function of importing/exporting a list (that already takes care of how it’s stored internally for the single cache instance you mention) already exists so what would be added is the comparison with iCloud and the determining of actions based on the state of the sync. 

[Nic Hubbard]

On 1/13/2018 at 3:52 AM, ShammyLevva said:

Really not a terribly difficult process to add as a large part of the logic already exists. In particular the core function of importing/exporting a list (that already takes care of how it’s stored internally for the single cache instance you mention) already exists so what would be added is the comparison with iCloud and the determining of actions based on the state of the sync. 

You are largely underestimating the complexity of the Core Data technology on iOS and how it could sync with iCloud. To make things worse, Apple deprecated all of the APIs for this type of sync so I would not want to attempt to do this. Just Google "Core Data iCloud sync" and you will find hundreds of results talking about how it is a nightmare and never worked well. It is not just a matter of synching GPX files as any changes would cause large data usages to sync files.

There are other alternatives to the Apple provided APIs for sync but at this point it is just a "nice to have".