What should I pay attention to when preparing graphics for retina?

Question

iOS

Hi all!
I am a designer, I drew a screen for the retina, the developer asked me to reduce the logo and all graphics by 50%, after which I uploaded it. The logo in the application looks stretched and not kosher, not like in Photoshop.
Friends, please help, maybe there are some rules or features that you should pay attention to when preparing graphics.
Thank you in advance!

Answer 1

On my own, I would add that thin lines can look "blurry" at 50% reduction in the layout if they were in an odd position on the retina picture. For example: at the y coordinate = 11. But I think this would be noticeable at the layout stage.
If the layout meets the requirements, then on the device, provided that the layout is correct, you get the expected result.

Answer 2

what do we do? macos app? web?
in any case - there should be an image with the appropriate detail - if a raster then with the desired size in pixels, if a vector - then the question would hardly have arisen
for the web, two images are often made - one for standard resolution, shown initially, the second - high resolution, loaded if determined that the retina

Answer 3

ugh, just noticed the "ios" tag
if for an iPhone - then what's the point of making a non-retina? under 3gs?