Generate iOS/macOS/watchOS App Icon without software or online tools.

You might have installed application like Prepo. But there are not all icon I needed. There are other application too but was paid. Just for this, I wanted to do it free. Are you searching free too? Well, you are the right place. I will show you free version and do some modification as you needed.

Steps

1. Copy this code

#!/bin/bash

set -e

spushd() {
     pushd "$1" 2>&1> /dev/null
}

spopd() {
     popd 2>&1> /dev/null
}

info() {
     local green="\033[1;32m"
     local normal="\033[0m"
     echo -e "[${green}INFO${normal}] $1"
}

cmdcheck() {
    command -v $1>/dev/null 2>&1 || { error >&2 "Please install command $1 first."; exit 1; }   
}

error() {
     local red="\033[1;31m"
     local normal="\033[0m"
     echo -e "[${red}ERROR${normal}] $1"
}

warn() {
     local yellow="\033[1;33m"
     local normal="\033[0m"
     echo -e "[${yellow}WARNING${normal}] $1"
}

yesno() {
    while true;do
    read -p "$1 (y/n)" yn
    case $yn in
        [Yy]) $2;break;;
        [Nn]) exit;;
        *) echo 'please enter y or n.'
    esac
done
}

curdir() {
    if [ ${0:0:1} = '/' ] || [ ${0:0:1} = '~' ]; then
        echo "$(dirname $0)"
    elif [ -L $0 ];then
        name=`readlink $0`
        echo $(dirname $name)
    else
        echo "`pwd`/$(dirname $0)"
    fi
}

myos() {
    echo `uname|tr "[:upper:]" "[:lower:]"`
}

#########################################
###           GROBLE DEFINE           ###
#########################################

VERSION=2.0.0
AUTHOR=smallmuou
MODIFIED=immortalsantee

#########################################
###             ARG PARSER            ###
#########################################

usage() {
prog=`basename $0`
cat << EOF
$prog version $VERSION by $AUTHOR modified by $MODIFIED

USAGE: $prog [OPTIONS] srcfile dstpath

DESCRIPTION:
    This script aim to generate iOS/macOS/watchOS APP icons more easier and simply.

    srcfile - The source png image. Preferably above 1024x1024
    dstpath - The destination path where the icons generate to.

OPTIONS:
    -h      Show this help message and exit

EXAMPLES:
    - ./$prog 1024.png ~/123
    - sh $prog 1024.png ~/123
    - bash $prog 1024.png ~/123
    
EOF
exit 1
}

while getopts 'h' arg; do
    case $arg in
        h)
            usage
            ;;
        ?)
            # OPTARG
            usage
            ;;
    esac
done

shift $(($OPTIND - 1))

[ $# -ne 2 ] && usage

#########################################
###            MAIN ENTRY             ###
#########################################

cmdcheck sips
src_file=$1 # source path
dst_path=$2 # destination path

# check source file
[ ! -f "$src_file" ] && { error "The source file $src_file does not exist, please check it."; exit -1; }

# check width and height of source file provided
src_width=`sips -g pixelWidth $src_file 2>/dev/null|awk '/pixelWidth:/{print $NF}'`
src_height=`sips -g pixelHeight $src_file 2>/dev/null|awk '/pixelHeight:/{print $NF}'`

[ -z "$src_width" ] &&  { error "The source file $src_file is not a image file, please check it."; exit -1; }

if [ $src_width -ne $src_height ];then
    warn "The height and width of the source image are different, will cause image deformation."
fi

# create dst directory 
[ ! -d "$dst_path" ] && mkdir -p "$dst_path"

# ios sizes refer to https://developer.apple.com/design/human-interface-guidelines/ios/icons-and-images/app-icon/
# macos sizes refer to https://developer.apple.com/design/human-interface-guidelines/macos/icons-and-images/app-icon/
# watchos sizes refer to https://developer.apple.com/design/human-interface-guidelines/watchos/icons-and-images/home-screen-icons/
# 
# 
# name size
sizes_mapper=`cat << EOF
Icon-16         16
Icon-16@2x      32
Icon-32         32
Icon-32@2x      64
Icon-128        128
Icon-128@2x     256
Icon-256        256
Icon-256@2x     512
Icon-512        512
Icon-512@2x     1024
Icon-20         20
Icon-20@2x      40
Icon-20@3x      60
Icon-29         29
Icon-29@2x      58
Icon-29@3x      87
Icon-40         40
Icon-40@2x      80
Icon-40@3x      120
Icon-60@2x      120
Icon-60@3x      180
Icon-76         76
Icon-76@2x      152
Icon-83.5@2x    167
Icon-1024       1024
Icon-24@2x      48
Icon-27.5@2x    55
Icon-86@2x      172
Icon-98@2x      196
Icon-108@2x     216
Icon-44@2x      88
Icon-50@2x      100
EOF`

OLD_IFS=$IFS
IFS=$'\n'
srgb_profile='/System/Library/ColorSync/Profiles/sRGB Profile.icc'

for line in $sizes_mapper
do
    name=`echo $line|awk '{print $1}'`
    size=`echo $line|awk '{print $2}'`
    info "Generate $name.png ..."
    if [ -f $srgb_profile ];then
        sips --matchTo '/System/Library/ColorSync/Profiles/sRGB Profile.icc' -z $size $size $src_file --out $dst_path/$name.png >/dev/null 2>&1
    else
        sips -z $size $size $src_file --out $dst_path/$name.png >/dev/null
    fi
done

info "Congratulation. All icons for iOS/macOS/watchOS APP are generate to the directory: $dst_path."

IFS=$OLD_IFS

2. Once you copy the code, open terminal and enter following command.
   • nano /usr/local/bin/smicon
3. You will see old fashioned text editor. Just press command + v to paste the code.
4. After pasting the code, follow these steps.
   1. Press control + x
   2. Press y
   3. Press enter

Now you can execute smicon command from anywhere. This means, you have installed the app. here are the steps to create app icon.

1. cd directory/to/your/appicon/folder
2. bash smicon app.png ./
   • ./ is your destination path. It will generate files in current folder.
   • You can also type smicon app.png ./convert
     • ./convert creates a folder with name convert.

If you want to add new sizes you can add as shown in image.

And boom🤯💥. That’s all. Let me know if you find any issue. I will help you. 👽.

Thanks