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The vCard format has a UID subject which ought to uniquely determine a contact to keep away from duplicates. This works: when importing the identical vCard twice with a number of contacts inside and a hard and fast UID for every, it’s going to acknowledge those that exist already and never add duplicates.
Nonetheless, iOS contacts will duplicate all fields contained in the contact: the telephone quantity and e mail deal with of this contact will likely be there twice. Each the sector label (work telephone quantity, for instance) and its worth are an identical.
The format additionally has a revision (REV) subject however this seems to be unused. Importing a vCard with the identical REV worth twice, which ought to point out that the info hasn’t modified within the meantime, the fields are nonetheless being duplicated.
The REV and UID fields aren’t exported when sharing a contact, making me suspect that iOS does not take them into consideration in any respect.
The one answer that I see is that the exporter, the creator of the vCard file, must by some means know per system which fields exist already and omit these from the file. Updating a subject doesn’t appear to be doable in any respect.
Is there any option to create a vCard that can ignore already-existent fields or, even higher, replace them in the event that they modified? I’ve not been capable of finding any documentation relating to Apple’s dealing with of vCard information on iOS.
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