2.5 years of mac and iOS development and i haven't found an answer to something.
I'm working on a project utilizing iOS 5.0 and apple TV's airplay to display one UIScreen on the iPad and a separate one on my Apple TV. I have 2 separate view controllers and they display fine on each respectively.
The issue is that the apple tv screen size returns at 720p not 1080p. So i get a bordered view controller at 1280 X 720 displayed and not a full screen representation of 1920 x 1080. The effect is my view controller is cropped not scaled.
I tried the naughty things like changing screen bounds of the UIScreen and the view controller bounds but that doesn't work.
Simply put:
Does iOS 5 support a full screen 1080p view controller to be displayed? if so how did you do it?
EDIT:
So the question is modified that if only 720p is possible to display then how do i get the app to display its view controller fullscreen and not cropped/letterboxed?
Apple TV only supports 720p, but it should be noted that the Digital AV Adapter supports 1080p (1920x1080). I suspect that if a next gen Apple TV is released, it will support 1080p and may support displaying it over AirPlay.
That issue aside, I faced exactly the same problem as you - I was pulling my hair out trying to figure out why my view was inset when displaying both via the Digital AV Adapter and over Airplay on my Samsung TV. I finally figured out that it was an issue with how my TV was configured for the ports that I was using. When I found the "Just Scan" option for the relevant inputs, it solved the problem and I got a perfect edge-to-edge image. The 1080p output using the Digital AV Adapter is gorgeous and I'm having lots of funny creating an app that leverages it.
In the process of investigating, I learned about the new iOS 5.0 overscanCompensation property of UIScreen (http://developer.apple.com/library/IOs/#documentation/UIKit/Reference/UIScreen_Class/Reference/UIScreen.html). This was not the source of my difficulties, but you might want to play with it's settings to see if it solves your issue.
Since the apple TV does not support 1080p (only 720p) it won't work.
Take a look at his tech specs: http://store.apple.com/us/browse/home/shop_ipod/family/apple_tv
Update: The newest apple TV now supports 1080p.
来源：https://stackoverflow.com/questions/8122212/ipad-mirroring-using-2-screens-does-it-support-1080-resolution