Keeping a long-term reference to an IOS AddressBook entry

Question

Given that an ABRecordID can change between cloud syncs and under other circumstances out of my control, how can I maintain a long-term reference to an IOS address book reco

Answer 1

The most robust (yet not completely failsafe) approach would be to come up with a priority ranking of ABRecord fields and store as much from that list as is available, along with the ABRecordID, into your own (hashed) private record format. When retrieving a private record (or at another convenient time), you can verify that the private record matches the ABRecord and work through a series of fallback checks to ensure it's accurate.

Example priority ranking:

1. ABRecordID
2. FirstName
3. LastName
4. PhoneNumber
5. ZipCode

When retrieving a record you can first match the ABRecordID. If that returns no results, you can do a search for FirstName + LastName. You can then match those results against PhoneNumber... etc. In this way you could potentially distinguish between 2 Bob Smiths, as they may have different phone numbers (or one may not have a phone number). Of course, depending on how long your priority list is, the more robust this mechanism will be.

The last resort would be prompting the user to distinguish between 2 Bob Smiths with brand new ABRecordID's whose records are otherwise identical -- after all, such an inconvenient prompt would be far more friendly than allowing the User to contact the wrong Bob Smith (and as I said, would be a last resort).

This solution for AB may involve some synchronization issues, however.

This is a familiar problem for anyone who has worked with the iOS Media Player. Specifically MPMediaItems in the User's Music Library have a property MPMediaItemPropertyPersistentID which the docs describe as:

The value is not guaranteed to persist across a sync/unsync/sync cycle.

In other words, the PersistentID is not guaranteed to be persistent. Solutions for this include doing similar fallback checks on MediaItem properties.