If your car gets broken into or stolen, your renters insurance will cover your personal property in the car, but if you have a high deductible you might be better off not filing a claim.
Also, filing a claim may increase the possibility of a higher premium during renewal. Therefore, you should also think twice before filing the claims depending on the value of the stolen iPhone.
The information in this answer is general in nature and is not legal or insurance advice for your specific situation. Policy language varies carrier by carrier; your declarations page is the final word. If you're unsure, call your agent before you need to file.