Is it considered unlawful if I buy a police scanner on iPhone in the state of Florida?

I was arrested recently for having a Police Scanner on my iPhone and the i was charged with unlawful installment of a police scanner. But it wasn't unlawful because it was plugged into a AUX cord to my car. And now the Ft.Lauderdale police department doesn't want to give me back my iPhone. And the stat attorney office is suppose to file the charge if there is one to be file. but i need some legal advise