问题
I've seen tons of questions and answers regarding merging an iPhone and an iPad app into an universal app, but that isn't what I want to do. What I am going to do is use in app purchase to unlock an iPad interface and then display the correct interface using conditionals. If the interface is purchased, the app displays the iPad Nib, and if not, it just displays the same way as an iPhone application does (with the option to scale the app, etc). The conditionals are very simple and I have already implemented them, however the issue I run into is this: If the IAP is NOT purchased, the iPad displays the iPhone Nib, but not in the typical way. It is just in the corner with no option to scale it, rather than in the center with the black border that you usually see. Does anyone know how I can set it up so i fixes this issue? I'm a little stumped to be honest.
回答1:
The Info.plist file in an iOS app contains a key, UIDeviceFamily, which lists the devices that the app natively supports. If the key's value is 1, or a array containing 1, the app natively supports iPhones and iPods Touch. If the value is 2, or a array containing 2, the app natively supports iPads.
If UIDeviceFamily says the app supports iPads, then it will run the app in native iPad mode, not in iPhone-wrapper mode.
The Info.plist file is part of your app bundle, and you can't modify files in the app bundle.
So there is no way to enable or disable the system's native-iPad support at runtime. You'll have to move your app's top-level view into a wrapper view that centers and scales its child, and use that wrapper view as the UIWindow's subview.
UIDeviceFamily in the Information Property List Key Reference
回答2:
This isn't possible, unfortunately. The iPad will know that the app is iPad ready and will tell draw the screen at full size. Even if you showed iPhone xib file on the iPad, they would still be scaled to fit the full screen using the UIViewAutoresizingMask params you've set for them.
One thought would be to force the size of your UIWindow to be iPhone sized (remember to account for retina) and centered, but I'm not 100% sure how/if this would work. You may have to change each UIView frame. I'm not sure.
来源：https://stackoverflow.com/questions/10804047/running-a-universal-app-as-a-scaled-iphone-app