Even in places with average crime rates, solving crimes looks good and if you've got the means to arrest someone for theft that makes you look good as a result.
Obviously if your day-to-day as a police officer involves the cartels or something you won't care about an iPhone. But if you live someplace where a murder would make the news regardless of the circumstances, someone will probably look into it if you can prove you know where the thief is (or that the phone was in a given house/apartment).
Yup, not only does it 'look good', but it gets a low level criminal off the street, sends a message to other people in similar circumstances, and (contrary to some beliefs) most cops actually like arresting criminals and returning stolen property.
Obviously if your day-to-day as a police officer involves the cartels or something you won't care about an iPhone. But if you live someplace where a murder would make the news regardless of the circumstances, someone will probably look into it if you can prove you know where the thief is (or that the phone was in a given house/apartment).