iPhone apps on ipad

[phantoms]

How come some iPhone apps when put on iPhone automatically turn to iPad apps?
Example cut the rope I have on iPhone and synced to my new iPad today and it was full screen and all like it would be if I bought for the iPad? Also reversi pro turned into reversi hd. And it's not the same with angry birds?

 

[cwerdna]

http://devimages.apple.com/iphone/resources/introductiontouniversalapps.pdf

 

[andybrown44]

When you download an app, if it has a + sign on the price of it, it means it is an iPhone and iPad app contained within one file. Some developers like to do this, some create completely separate apps, such as Angry Birds. This can be for various reasons, but I suspect the main one is additional revenue.

 

[AppleMacDudeG4]

Universal apps

As was previously mentioned, some developers create what is called a universal app. The app is able to recognize which device it is running on and will run itself based on the device. I would tend to think that creating a universal app is not as easy as creating a separate app for each which is why not all apps are written to be universal.