As of version 5.1 for iOS, the option “Share Interactions” is available in “Threema > Settings > Privacy > iOS Integration.” If activated, the operating system has access to information about interactions, i.e., iOS will learn which Threema ID you often exchange messages with. If available, an iOS-specific contact ID will also be shared. (Threema receives this contact ID from iOS when the Threema contact is linked to an iOS contact.)
The OS uses this information to suggest Threema contacts you regularly chat with in Siri suggestions, in Search, and when sharing content in other apps. If the option is activated, it is also possible to choose individual Threema contacts in Focus filters, or to set Threema as preferred messaging channel in the Contacts app (long tap on “message” below a contact’s name, and select Threema). However, granting access to this information will generate metadata. According to Apple, this metadata will only be managed on the user’s device and not synced with other devices.
