Iowa Code § 804.15: Breaking and entering premises — demand to enter.

If a law enforcement officer has reasonable cause to believe that a person whom the officer is authorized to arrest is present on any private premises, the officer may upon identifying the officer as such, demand that the officer be admitted to such premises for the purpose of making the arrest. If such demand is not promptly complied with, the officer may thereupon enter such premises to make the arrest, using such force as is reasonably necessary.