An icon resizing script for iOS projects.

icon-resizer.sh

#!/bin/bash

# About
# This script will resize your original app icon into all needed
# icon sizes. Images will be created in the same folder as this
# script. From there you just need to drag them to the appropriate
# image locations in Xcode.
# 
# Usage
# 1. Move this script and your source image into the same directory.
# 2. Make sure this script is executable with `chmod +x icon-resizer.sh`.
# 3. Call script with `./icon-resizer.sh originalAppIcon.png`

f=$(pwd)

# 20
sips --resampleWidth 20 "${f}/${1}" --out "${f}/AppIcon20.png"
sips --resampleWidth 40 "${f}/${1}" --out "${f}/AppIcon20@2x.png"
sips --resampleWidth 60 "${f}/${1}" --out "${f}/AppIcon20@3x.png"

# 29
sips --resampleWidth 29 "${f}/${1}" --out "${f}/AppIcon29.png"
sips --resampleWidth 58 "${f}/${1}" --out "${f}/AppIcon29@2x.png"
sips --resampleWidth 87 "${f}/${1}" --out "${f}/AppIcon29@3x.png"

# 40
sips --resampleWidth 40 "${f}/${1}" --out "${f}/AppIcon40.png"
sips --resampleWidth 80 "${f}/${1}" --out "${f}/AppIcon40@2x.png"
sips --resampleWidth 120 "${f}/${1}" --out "${f}/AppIcon40@3x.png"

# 60
sips --resampleWidth 120 "${f}/${1}" --out "${f}/AppIcon60@2x.png"
sips --resampleWidth 180 "${f}/${1}" --out "${f}/AppIcon60@3x.png"

# 76
sips --resampleWidth 76 "${f}/${1}" --out "${f}/AppIcon76.png"
sips --resampleWidth 152 "${f}/${1}" --out "${f}/AppIcon76@2x.png"

# 83.5
sips --resampleWidth 167 "${f}/${1}" --out "${f}/AppIcon83_5@2x.png"

# 1024
sips --resampleWidth 1024 "${f}/${1}" --out "${f}/AppIcon1024.png"