@andioak -- no don't do this. Inserting your own icons in a mac build will cause it to fail to notarize (well that's my experience anyway,,).

Aha, thanks for that caveat! :) So if i´m deadly serious about rez-snaz I gotta go into the hise source and add some if:s. Not sure that the amazing feeling seeing my logo in 8k instead of 4k is worth that atm. But one fine day, it shall shine.

Can anyone confirm that using the "Icon.png method" produces a stand alone that will pass notarization?

# shell script for creating an icon for an application from a set of input images

input_filepath="icon_name_1024_x_1024.png"
output_iconset_name="outputicon.iconset"
mkdir $output_iconset_name

sips -z 16 16     $input_filepath --out "${output_iconset_name}/icon_16x16.png"
sips -z 32 32     $input_filepath --out "${output_iconset_name}/icon_16x16@2x.png"
sips -z 32 32     $input_filepath --out "${output_iconset_name}/icon_32x32.png"
sips -z 64 64     $input_filepath --out "${output_iconset_name}/icon_32x32@2x.png"
sips -z 128 128   $input_filepath --out "${output_iconset_name}/icon_128x128.png"
sips -z 256 256   $input_filepath --out "${output_iconset_name}/icon_128x128@2x.png"
sips -z 256 256   $input_filepath --out "${output_iconset_name}/icon_256x256.png"
sips -z 512 512   $input_filepath --out "${output_iconset_name}/icon_256x256@2x.png"
sips -z 512 512   $input_filepath --out "${output_iconset_name}/icon_512x512.png"

iconutil -c icns $output_iconset_name

rm -R $output_iconset_name

I mean if one is to be a good boy and future-proof the icons on mac with all the resolutions (retina, 4k, 5k, 8k etc)

So can I just use a icon.icns instead?
@Christoph-Hart

A large png file is sometimes not that pretty once it is downsized, can be blurry.

Just put a square PNG image called exactly Icon.png in the Image directory and it will use this as icon. The resolution doesn't matter, but I recommend using at least 256x256.

I know this is late, but still so relevant. Has there been added any more support for OS-specific app icon image types? For example, on macOS you would use a .icns made in multiple sizes using the terminal app "iconutil". Nothing comes up on a search in the docs.

1- i didn't think that was so simple !
2 - yes, all icons are arlready 256px max (most of time it's 128px)

EDIT: tried, tested and .... work perfectly ! that rocks !
Christoph i tell you for the last time now !!!! stop ruling the world with HISE please !!! ;)