Previously, an app like Instagram or WhatsApp would request access to your contacts, and you could either grant access or deny it. There was no other option.

But iOS 18 complicates matters a lot. If an app requests access to your contacts after an update, you can select exactly which contacts you’re okay sharing.

On the face of it, this seems like a good idea, but like most things Apple, it is about knifing rivals for an extra buck.  The permissions tweak could pose significant problems to social apps that rely on contact sharing. Especially new social apps that are trying to break into a crowded market.

One start-up founder, Nikita Bier, said that contact sharing had dropped dramatically since the iOS 18 changes went into effect and that for some apps, the number of users sharing ten or fewer contacts had increased as much as 25 per cent. Other developers said their apps had experienced similar declines, though nobody except Bier would agree to speak on the record out of fear of a visit from the Jobs’ Mob black shirts.

A 25 per cent decline in contact sharing might not sound like a huge change. However, for social apps, the ability to quickly connect new users with their friends can mean the difference between success and failure.

Facebook discovered during its early days that users who added seven friends within ten days of signing up for an account were more likely to stay than users who didn’t.