How do I know that the contacts have been modified, if the application was not active on iOS?

Question

I need to run a function when the contacts have changed. If the application is active, you can do this with NotificationCenter as narrated in this post (sometimes It works when I add a new number to an existing contact). How do I know that the contact (or contacts) have been changed after the launch of the application?

I don't think the OS notifies you of any changed to the contact store. Try hashing the contact identifiers (Or attributes that you need to check that have changed) and when the application is launched and hash them again when needed. — Sealos, Jan 09 '17 at 09:51
@Sealos I'll do so, I just thought that suddenly there is a solution better than that. — Alexander Khitev, Jan 09 '17 at 10:01

score 2 · Accepted Answer · answered Jan 24 '17 at 20:07

I made the following functions for my task

  @objc private func matchingContacts() {
        if isSuccessContactUploading {
            contactManager.matchingContacts(notMatch: { [weak self] in
                guard let _self = self else { return }
                debugPrint("matchingContacts != equals")
                _self.isSuccessContactUploading = false
                _self.syncContacts()
            })
        }
    }

These functions are in ContactManager

   func matchingContacts(notMatch: (() -> Void)?) {
        getContacts { (contacts, error) in
            if error == nil {
                debugPrint("contacts count", contacts.count)
                self.getContactsDictionaryFromCache(contacts, notMatch: {
                    notMatch?()
                })
            }
        }
    }

 private func getContactsDictionaryFromCache(_ contacts: [CNContact], notMatch: (() -> Void)?) {
        var isMatching = true
        for contact in contacts {
            let key = contact.identifier

            do {
                let cache = try Cache<NSDictionary>(name: "Contacts")
                if let contactDictionary = cache[key] {
                    if !contactDictionary.isEqual(to: contact.dictionary) {
                        debugPrint("contactDictionary not matching")
                        isMatching = false
                    }
                } else {
                    debugPrint("contactDictionary isn't here")
                    isMatching = false
                }
            } catch {
                debugPrint(error.localizedDescription)
                isMatching = false
            }
        }

        if !isMatching {
            notMatch?()
        }

        cacheContacts(contacts)
    }

private func cacheContacts(_ contacts: [CNContact]) {
        for contact in contacts {
            let contactDictionary = contact.dictionary as NSDictionary
            let key = contact.identifier

            do {
                let cache = try Cache<NSDictionary>(name: "Contacts")
                cache[key] = contactDictionary
            } catch {
                debugPrint(error.localizedDescription)
            }
        }
    }

How do I know that the contacts have been modified, if the application was not active on iOS?

1 Answers1