The warrant must be directed to any peace officer in the state; give the name of the defendant, if known to the magistrate; if unknown, may designate "name unknown"; and must state by name or general description an offense which authorizes a warrant to issue, the date of issuing it, the county or city where issued, and be signed by the magistrate with the magistrate's name of office.
Iowa Code § 804.2
See R.Cr.P. 2.36 - Forms 5, 6, 7