Display Size? [iOS]

I am designing a game for iOs and needed some advice..

nowadays it seems like less iPhones has a 480 by 320 display, I am not really sure how to build my games and what size I should build them for. Does anyone have any advice?

It's hard to answer that question as it's very game specific, and it's something you'll have to plan (as long as you understand the scaling modes).  The only one-size-fits-all mode that Apple approves of (no letterboxing) is stretch to fit, but many developers find the stretching to be unacceptable.

The only one-size-fits-all mode that Apple approves of (no letterboxing) is stretch to fit, but many developers find the stretching to be unacceptable.

The new full screen mode doesn't work?

Basically, I treat iPhone design like HDTV. The station identification logos aren't always in the bottom right corner anymore. They're usually a bit towards the center. That way, on 4:3 TVs, the edges are cut off – but the logo still stays on the screen.

By positioning HUD elements dynamically, the old iPhones can be supported. I still use an iPhone 4.

It's hard to answer that question as it's very game specific, and it's something you'll have to plan (as long as you understand the scaling modes).  The only one-size-fits-all mode that Apple approves of (no letterboxing) is stretch to fit, but many developers find the stretching to be unacceptable.

there are the two blocks for running on a 3.5 Inch iPhone or running on a 4 inch.. However actor sizes may vary so I am a little confused as to how I would change the actor sizes from a 3.5 to a 4.. is there a  way to shrink all the actors animations... do i make any sense?

The new full screen mode doesn't work?

It's fine, but I guess I should have clarified what I meant.  For stretch to fit, you can use a 480x320  resolution, your scene size can be the same size, you won't have to reposition any actors, and it will fit all devices.  The two full screen modes require larger scene sizes (depends on your resolution) as well as actor adjustment in most cases.

my fear is that if i design for for 480 x 320 the actors will look stretched on a bigger display

Yeah they will, which is why many developers choose a better looking but more difficult scaling mode.  Try "scale to fit (full screen)" with a resolution of 480x320 and a scene size of at least 568x360.  You'll have to figure out the best way to position your actors for the different devices.