Document how to compress (macOS) icons without the recompression issue

[lwouis]

Hi,

Thanks for sharing these tools! I noticed this line in the readme:

building for macOS may end up with an ICNS or TIFF file, undoing PNG optimisation

It is indeed an issue I faced while developing my app. However, I found a solution: instead of using the built-in iconutil tool from Apple, one can use this third-party createicns tool which does the same thing, except it will not recompress the icons, thus keeping the size savings. You can see in this diff how easy it is to switch from one tool to the other. Note that I'm talking about macOS. I'm not sure how this plays out for iOS.

I struggled a bit to find this tool, and I think it would benefit from more visibility 👍

Thank you

[marcedwards]

Ah, thanks! That’s good to know. Optimage can also be used to compress ICNS files further (run it after creating the ICNS, rather than on the source PNGs).

https://optimage.app

iOS uses PNGs. Xcode can be configured to disable the recompression. I should add that to the help docs. The ImageOptim site has a great page on how to do it though:

https://imageoptim.com/xcode.html

[lwouis]

Thanks for sharing Optimage. It seems to do slightly better than ImageOptim. It's paid software though.

The tips for iOS are very interesting. I wish there was similar configuration for macOS.