Redirect iPhone to an special theme

how can i redirect iPhone-users to an iPhone theme without a plugin or a theme swiutcher. My idea is, that i detect the user agent (iphone) and this will be set something that i see an other theme i开发者_开发技巧n the iPhone.

Thanks and kind regards,

Peter

A plugin is really the best way to do this. There's an already phenomenal one called WPTouch. It has a very functional free and a paid pro version.