In order to provide for the uniform application of the provisions of this chapter relating to obscene material applicable to minors within this state, it is intended that the sole and only regulation of obscene material shall be under the provisions of this chapter, and no municipality, county or other governmental unit within this state shall make any law, ordinance or regulation relating to the availability of obscene materials. All such laws, ordinances or regulations shall be or become void, unenforceable and of no effect on January 1, 1978. Nothing in this section shall restrict the zoning authority of cities and counties.
Iowa Code § 728.11