Can they legally take it back?

Someone I know found an iPhone somewhere and they posted it on fb to see if anyone would come forward and claim it but no one did so they went on holiday(hence why they didn't take it to the police) when they got back it still hadn t been claim so he reset it(it didn't have find my iPhone on so the activation lock wasn't onit) made up a new Apple ID and is now using it, it has now been almost a year and the original owner now wants it back. Can they just legally take it after so long

Added (1). AS THE QUESTION STATES I'm NOT THE ONE HOLDING THE PHONE AND MY FRIEND HAS TRIED GETTING IN CONTACT WITH THE OWNER THE PAST WEEK AND HAS GOT NO REPLY, YES HE DID DO THE WRONG THING BY NOT TAKING IT TO THE POLICE AND HE SHOULDNT BE USING IT HAS HIS OWN BUT HE WENT ON HOLIDAY AND NOT TOOKVIT TO THE POLICE BECAUSE HE HAD THAT HOLIDAY BOOKED FOR WEEKS BEFORE FINDING THE PHONE. HE SAID HES GIVING THE OWNER A FEW MORE DAYS. THE PHONE WAS NEVER REPORTED LOST OR STOLEN.

I would assume so, after all it is theirs.

It still belongs to them

Yes, it is their phone. You are holding a phone that does not belong to and you have no receipt for. Key is the receipt which has the original owners and sim information.

Where you are makes a difference in this. Since we don't know, you'll want to consult a local solicitor/attorney

Yes, of course they can. Posting a message on Facebook does not make for a legitimate attempt to return the phone. It should have been turned into the police. Things do not suddenly become yours because time has elapsed.

Posting on Facebook probably does not count, and failure to notify the police and ask about reclaiming if no owner comes forward is bad - so YEAH if someone can prove it was theirs not only can they take it but your "friend" might be facing theft or possession of stolen property charges

No, they can't just legally take it, but they shouldn't have to. Your friend should be willing to return it. If he doesn't, the actual owner could choose to sue.

Most states have a set time you have to list it as found and it's yours. The problem you are going to have is Facebook isn't the prescribed way to post it. So right now he could be accused of receiving stolen property. The answer to that is I'd return it.

Posted it on fb?
Like people troll facebook hoping to see ads for lost iPhones?
Really?

Yes, it is their phone, and truth be told, your "friend" did all the wrong things.

You DID NOT come anywhere close to the legal definition of making a good faith attempt to contact, or even IDENTIFY the true owner. Until you do that, the clock doesn't even START of considering the item abandoned property. It is IMPOSSIBLE for phone with active service to be mildly difficult for the service provider to tie to the owner.
You actually BROKE THE LAW by keeping the item instead of turning it over to the police.