"become yours" - Which court are you in? The court of the schoolyard? If you're in real court, then
You would need to sue, to quiet title
When a bona-fide dispute as to ownership exists, a case can be brought before a judge to resolve ownership definitively.
The axiom of a quiet title action is that you must notify all parties who could possibly have an interest. Really, notification is 7/8 of it, because by the time you arrive at a "quiet title" action, most likely they either lost interest or are gone.
And the crux of "Notify" is that your efforts to notify the party are to the standards of the court. You are a hostile party, noting your interests are in conflict with theirs. (we must fairly assume they want their iPad back; you want to take the iPad). Thus, it is obvious you will prefer to fail in your efforts at contact, and you will do a bad job of it, possibly on purpose.
Since parties in a lawsuit are responsible to serve all documents on each other, courts have very high standards for that. And these standards are tested and gamed all the time. I even had a clever plaintiff do it to me! (we were expecting both the appeal and the dis-service).
The crux of document service is you hire a licensed, third-party independent process server. A process server is naturally good at skip-tracing (think "Dog: the Process Server") and is accustomed to finding people who are actively hiding. (because some people think they can avoid consequences by evading service. That's a loser's game generally.)
So, when you show up in court and they aren't there, the judge will ask "did you serve them?" And then you say "yes", name the company, and if needed call the process server to the stand, and the server reads out of their notebook all the things they did to search for the counterparty.