Create Xcode iconset for macOS app from a 1024x1024 sized png file

create_xcode_icns.sh

#!/bin/sh

# ================================================
# create_xcode_icns.sh
#
# Create Xcode iconset for macOS app from a 1024x1024 sized png file
#
# Drag png file to Terminal window to get the file path as a parameter for the script
# Iconset will be created to the same folder where the original icon is
# Import (drag&drop) icns file to Xcode
# Edit Info.plist -> Icon file: icons_for_xcode
# ================================================

set -o nounset              # Exit script if variable is not set

### Vars
iconset_name="icons_for_xcode.iconset"
number_of_parameters=$#
all_parameters=( "$@" )

### Commands
sips="/usr/bin/sips"

###

function usage() {
    echo "Usage: $0 path/to/original-1024.png"
}

function preflight_checks() {
    
    # Check parameters
    if [ $number_of_parameters -eq 0 ]; then
        echo "ERROR: Missing parameter, png file path required."
        usage
        exit 1
    else
        orig_icon_file="${all_parameters[0]}"
        target_folder=$(dirname "$orig_icon_file")
        iconset_path="${target_folder}/${iconset_name}"
    fi

    if [[ ! -f "$orig_icon_file" ]]; then
        echo "ERROR: File not found: ${orig_icon_file}"
        usage
        exit 1
    fi
}

function create_icon_files() {

    # Create temp dir
    /bin/mkdir -p "$iconset_path"

    # Create files
    $sips -z 16 16     "$orig_icon_file" --out "$iconset_path"/icon_16x16.png
    $sips -z 32 32     "$orig_icon_file" --out "$iconset_path"/icon_16x16@2x.png
    $sips -z 32 32     "$orig_icon_file" --out "$iconset_path"/icon_32x32.png
    $sips -z 64 64     "$orig_icon_file" --out "$iconset_path"/icon_32x32@2x.png
    $sips -z 128 128   "$orig_icon_file" --out "$iconset_path"/icon_128x128.png
    $sips -z 256 256   "$orig_icon_file" --out "$iconset_path"/icon_128x128@2x.png
    $sips -z 256 256   "$orig_icon_file" --out "$iconset_path"/icon_256x256.png
    $sips -z 512 512   "$orig_icon_file" --out "$iconset_path"/icon_256x256@2x.png
    $sips -z 512 512   "$orig_icon_file" --out "$iconset_path"/icon_512x512.png
    /bin/cp "$orig_icon_file" "$iconset_path"/icon_512x512@2x.png

    # Convert .iconset -> .icns
    /usr/bin/iconutil -c icns "$iconset_path"

    # Delete temp folder
    # /bin/rm -r "$iconset_path"
}

#
preflight_checks
create_icon_files

exit $?