Apple - How to force a sync update between Gmail contacts and iPhone with iOS 9?

[update 2016-09-02] in iOS 9.3.5 you can simply pull down in the Contacts list to force a sync.

If this doesn't appear to work, make sure the problem is with syncing and not with the data iOS "sees" in the Google contacts by testing on a separate contact. For example, I had a problem (while on iOS 10.2) where the phone number wouldn't sync because it was in a wrong field of the Google contact.

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In earlier iOS versions there used to be a sync button in the upper-left corner of Contacts app, now it seems to be gone (though some claim it can reappear under certain circumstances). There also used to be a way to force sync by pulling down in the Contacts app -> Groups view, but it doesn't work for me (and others) in iOS 9.1 either. This discussions.apple.com thread is useful to see the evolution of this feature.

Luckily, there's another thread with a collection of weird workarounds to force a sync without toggling contacts sync off/on or restarting the device. The following two ways worked for me to force syncing with Google contacts on iOS 9.1:

• Going to Settings -> iCloud (which incidentally triggers Google sync(?!)), then switching to Contacts.
• Going to Settings -> Mail, Contacts, Calendars -> Gmail -> Account -> tap in any field (Name, Email or Description) but don't make any changes -> Done, switch to Contacts.

External account settings can be found under Settings-> Mail, Contacts, Calendars-> Fetch New Data.
Configure the frequency of synchronization on the bottom of the screen. It is possible to update in "real time" if "Push" is turned on, but this will have a negative impact on battery life.