When creating an app for iOS, you need to know about the platform you are working with, how it can work best on the platform, and the technical limitations of it. With the iPad and iOS, there are certain guidelines that must be adhered to when designing for it.
"Retina - Most recent iPhones and iPads are fitted with Retina screens, a high
resolution screen intended to make pixels invisible. The Retina
resolution of a device is an
exact doubling of the previous resolution.
A single pixel in a non-retina iOS device is taken up by four pixels in
the retina version. This makes text crisper and allows for
significantly more subtle detail. There are many complexities to
designing for retina screens, so this is an important area to read up
on."
"Pixels - A
pixel (px) is the
smallest unit of measurement
on a screen. It represents a minuscule physical square that is part of
the display. If you look very closely at a screen, you'll be able to see
them (and the gaps between).
It is
not possible to have a line that is smaller than "1px" in
width. For example a 0.4px line can't possibly exist, instead graphics
software interprets this as a fainter 1px line. This result is often
considered ugly."
"Points - We use
points (pt) as a
resolution independent measure.
A point can be represented by many pixels, normally one or two in a
single dimension (high or wide). For example all iPads have the same
resolution in points and all iPhones have the same width in points.
Over time you'll learn to think in points rather than pixels. But it's
important to remember that each point can be made of many pixels and so
there is room for extra detail."
http://taybenlor.com/2013/05/21/designing-for-ios.html
These are various things that should be kept in mind while designing for iOS. Retina screens are not in all iOS products, so users of both should be considered when designing for iOS.
Device |
Retina? |
Point Resolution (pt) |
Pixel Resolution (px) |
iPhone < 3GS |
|
320 x 480 |
320 x 480 |
iPhone 4, 4S |
eye |
320 x 480 |
640 x 960 |
iPhone 5 |
eye |
320 x 568 |
640 x 1136 |
iPad 1, 2 & Mini |
|
768 x 1024 |
768 x 1024 |
iPad 3, 4 |
eye |
768 x 1024 |
1536 x 2048 |