Universal App Development
A Universal app can determine which device itʼs running on and provide the best experience for that device. Well-designed Universal apps leverage a deviceʼs unique hardware features, provide the right choice of user interface elements, and use only the functionality that is supported by that device.
Apple recommends that iPhone OS developers design, code and build their applications as Universal applications. Building apps as Universal apps makes it easier for everyone. Itʼs easier for developers because thereʼs only one app to manage on the App Store. Itʼs easier for users because theyʼll know that it runs on any device they own.
Whether youʼre thinking of optimizing an existing iPhone application or creating a brand new one that takes advantage of iPad, you should take the opportunity to design your apps as Universal apps. An important approach to designing a Universal application for iPhone OS is to think about how user interaction can be separated from the underlying application code.The iPhone SDKʼs classes and APIs leverage a model-view-controller (MVC) paradigm that encourages a clean separation of your application data and logic from the views used to present that data. The ﬁrst step in making a Universal app is to create user interface designs for each of the form factors—one design for iPad devices and another for iPhone/iPod touch devices. Much of your design will be affected by the features you want to expose in each of the different form factors.