in iPhone App How to detect the screen resolution of the device

Question

In iPhone App, while running the App on device How to detect the screen resolution of the device on which App is running?

Answer 1

CGRect screenBounds = [[UIScreen mainScreen] bounds];

That will give you the entire screen's resolution in points, so it would most typically be 320x480 for iPhones. Even though the iPhone4 has a much larger screen size iOS still gives back 320x480 instead of 640x960. This is mostly because of older applications breaking.

CGFloat screenScale = [[UIScreen mainScreen] scale];

This will give you the scale of the screen. For all devices that do not have Retina Displays this will return a 1.0f, while Retina Display devices will give a 2.0f and the iPhone 6 Plus (Retina HD) will give a 3.0f.

Now if you want to get the pixel width & height of the iOS device screen you just need to do one simple thing.

CGSize screenSize = CGSizeMake(screenBounds.size.width * screenScale, screenBounds.size.height * screenScale);

By multiplying by the screen's scale you get the actual pixel resolution.

A good read on the difference between points and pixels in iOS can be read here.

EDIT: (Version for Swift)

let screenBounds = UIScreen.main.bounds
let screenScale = UIScreen.main.scale
let screenSize = CGSize(width: screenBounds.size.width * screenScale, height: screenBounds.size.height * screenScale)