Easily convert .jpg and .png to .icns with the command line tool icnsify, or use the library to convert from any image.Image to .icns.

go get github.com/jackmordaunt/icns

icns files allow for high resolution icons to make your apps look sexy. The most common ways to generate icns files are:

1. iconutil, which is a Mac native cli utility.
2. ImageMagick which adds a large dependency to your project for such a simple use case.

With this library you can use pure Go to create icns files from any source image, given that you can decode it into an image.Image, without any heavyweight dependencies or subprocessing required. You can also use it to create icns files on windows and linux (thanks Go).

A small CLI app icnsify is provided allowing you to create icns files using this library from the command line. It supports piping, which is something iconutil does not do, making it substantially easier to wrap or chuck into a shell pipeline.

Note: All icons within the icns are sized for high dpi retina screens, using the appropriate icns OSTypes.

preview is a gui for displaying icns files cross-platform.

go install github.com/jackmordaunt/icns/cmd/preview@latest

git clone https://github.com/jackmordaunt/icns
cd icns/cmd/preview && go install .

Note: Gio cannot be cross-compiled right now, so there are no preview builds in releases. Note: preview has it's own go.mod and therefore is versioned independently (unversioned).

go install github.com/jackmordaunt/icns/v2/cmd/icnsify@latest

scoop bucket add extras # Ensure bucket is added first
scoop install icnsify

Or from my personal bucket:

scoop bucket add jackmordaunt https://github.com/jackmordaunt/scoop-bucket 
scoop install jackmordaunt/icns # Name is defaulted to repo name. 

winget install icnsify

brew tap jackmordaunt/homebrew-icnsify # Ensure tap is added first.
brew install icnsify

git clone https://github.com/jackmordaunt/icns
cd icns && go install ./cmd/icnsify

Pipe it

cat icon.png | icnsify > icon.icns

cat icon.icns | icnsify > icon.png

Standard

icnsify -i icon.png -o icon.icns

icnsify -i icon.icns -o icon.png

go get github.com/jackmordaunt/icns/v2

func main() {
        pngf, err := os.Open("path/to/icon.png")
        if err != nil {
                log.Fatalf("opening source image: %v", err)
        }
        defer pngf.Close()
        srcImg, _, err := image.Decode(pngf)
        if err != nil {
                log.Fatalf("decoding source image: %v", err)
        }
        dest, err := os.Create("path/to/icon.icns")
        if err != nil {
                log.Fatalf("opening destination file: %v", err)
        }
        defer dest.Close()
        if err := icns.Encode(dest, srcImg); err != nil {
                log.Fatalf("encoding icns: %v", err)
        }
}

• Encoder: image.Image -> .icns
• Command Line Interface
  • Encoding
  • Pipe support
  • Decoding
• Implement Decoder: .icns -> image.Image
• Symmetric test: decode(encode(img)) == img

If this software is useful to you, consider buying me a coffee!

https://liberapay.com/JackMordaunt