changing format (for respond_to)

So in my action I have:

- respond_to do |format| - format.html - format.iphone - end

Now I can access action.html and action.iphone, however how would I make it default to the iPhone view if the user agent is an iPhone. I'm pretty tired so forgive me for being brief or perhaps missing something obvious. I tried having the code below as a before_filter, but that didn't work.

- if request.user_agent =~ /iPhone/ - params[:format] = 'iphone' - end

Anyway, thanks for your time :slight_smile: