How to create images for images.xcassets?

Question

Objective-C

I have a picture, how can I make the necessary pictures for all the eras through Photoshop?
Do you need to change only the pixels in the picture? Or resolution too?
Please write the parameters for each 1x,2x,3x

Answer 1

1x - by 1 point 1 pixel
2x - by 1 point 2 pixels (Retina)
3x - by 1 point 3 pixel (Retina HD)
For example, your application only supports portrait mode for iphone 4+ devices, then you make resolutions in such a way.
320 x 480 for portrait (iPhone 4*)
640 x 1136 (@2x) for portrait (iPhone 5*)
750 x 1334 (@2x) for portrait (iPhone 6)
1242 x 2208 (@3x) for portrait (iPhone 6 plus )
If my memory serves me, then images.xcassets just provides a convenient interface for comparing images
of device
resolution device resolution 2
apple dock