iOS: Preparing background images for applications

Question

Mostly every iOS application has a view with an image as background. Is there any image sizing guide out there? For example here is an iOS screen designed in Sketch:

Answer 1

There are 3 kinds of Apple Devices (iPhone and iPad) that is

Normal device which terms to 1 pixel = 1 point@1x (Older iPhone and iPad devices)

Retina device which terms to 4 pixels(2 x 2) = 1 point@2x (iPhone 5+)

Retina iPhone6 and iPad which terms to 9 pixels (3 x 3) = 1 point@3x (iPhone6+)

For iOs 10 that will not support iPhone 4s so you only require @2x and @3x images.

As you can see above attached image iPhone 6 also support @2x Scale so use image size for @2x is of 750*1334 and for @3x is of 1242*2208 with image mode.