Command line script to resize an iOS app icon to all the sizes specified by Apple.

iair.sh

#!/bin/bash

# Takes a 1024x1024 app icon and produces all app icon sizes based on it.
# Requires imagemagick to work.
# USAGE iair ORIGINAL_FILE PATH_TO_OUTPUT_DIR
# Example: iair icon.png .

original_file=$1
output_dir=$2

if [ ! -f $original_file ]; then
	echo 'File $original_file not found'
	exit
fi

#Array of all required sizes
declare -a sizes=("16"
                  "29"
                  "32"
                  "40"
                  "48"
                  "50"
                  "55"
                  "57"
                  "58"
                  "64"
                  "72"
                  "76"
                  "80"
                  "87"
                  "88"
                  "100"
                  "114"
                  "120"
                  "128"
                  "144"
                  "152"
                  "167"
                  "172"
                  "180"
                  "196"
                  "256"
                  "512"
                  "1024")

for size in ${sizes[@]}
do
  convert $original_file -resize $size'x'$size "$output_dir/Icon-$size.png"
done