Im creating an App for iPhone5 and it runs good in iPhone 6.0 simulator (with 4-inch display). Now i wanna test it on my New iPad, which has been upgrade to iOS6, but the screen is automatically shrinking into 3.5-inch. Is there anyway to keep the screen being 4-inch on New iPad? Thanks in advance:)
The "compatibility mode" on iPad runs iPhone-only apps in their 320x480 format—in essence, it is compatible with iPhone <5. There is no way to make it compatible with the 320x568 format used by iPhone 5 and iPod touch (3rd Gen).
So it will always run with your app’s "standard" layout, not the "high" one.
Thus, the short answer is "no".