In this chapter, you will learn how to design an app with an interface for multiple devices. You will be introduced to all of Apple’s devices and device sizes. This chapter will give you a foundation in app design so that you can start designing the user interface for your own apps.
iOS runs on many different device sizes and formats, including iPhone, iPod Touch, iPad, and iPad Mini. Table 7-1 contains all of these devices and their size in pixels.
|Device||Height (px)||Width (px)|
iPhone 4 (Retina)
iPhone 5 (Retina)
iPhone 6 (Retina)
iPhone 6 Plus (Retina HD)
iPad w/ Retina
iPad Mini w/ Retina
Pixels represent the drawable units on a display, just like the boxes on a sheet of graph paper. As devices have evolved, more and more pixels have been added. This creates a more dense area of pixels, providing more detail for each square inch of the device. This pixel-per-inch (PPI) is the standard for measuring the density of a display. When Steve Jobs announced the iPhone 4, he claimed the human eye could not notice the difference above a 300 PPI display. The iPhone 4 boasted a 326 PPI, and the term Retina has been used to describe any PPI over 300. The iPhone 6 Plus boasts a 401 PPI Retina HD display.
To help manage the Retina and Retina HD images for your application, Apple has provided some filenaming keywords: