The complaint is a written statement of the essential facts constituting the offense charged. It must be made on oath before a magistrate; except that, a prosecuting attorney may sign a complaint before a magistrate, without oath or affirmation, based on a sworn affidavit or declaration. Any affidavit or declaration supporting an unsworn complaint must be filed with the court. Except as otherwise provided by law or rule, all criminal proceedings must be initiated by complaint or indictment and prosecuted by complaint, indictment or information as provided by these rules.