Generate iOS Launch or splash screen from a single image

generateLaunchScreen.sh

#!/bin/bash -e

# --------------------------------------------------------
# Generate iOS Launch items from a single image
# (c) 2017 ePi Rational, Inc.
#
# Modified from original script which generated app icons for iOS,
# originally written by
# Ben Clayton, Calvium Ltd.
#  https://gist.github.com/benvium/2be6d673aa9ac284bb8a
# --------------------------------------------------------

# Process
# As of 2017, the largest launch screen for iOS is.
# 12.9-inch iPad Pro | 2048px by 2732px | `Default-1366h@2x.png`
# 12.9-inch iPad Pro | 2732px by 2048px | `Default-Landscape-1366h@2x.png`
#
# The idea is to create a portrait and landscape at the above sizes,
# then use ImageMagick to scale.
# ImageMagick steps
#   * create a white background with the desired image extent
#   * scale the large image, while tending towards the center
#   * testing showed that the `-resize` alone did not properly create the final image sizes. 

# Check imagemagick is installed
# http://stackoverflow.com/questions/592620/check-if-a-program-exists-from-a-bash-script
command -v convert >/dev/null 2>&1 || { echo >&2 "Requires imagemagick, but it's not installed.  See http://www.imagemagick.org.  Aborting."; exit 1; }

# Uses the largest images as the base image for generating the others
portrait="Default-1366h@2x.png"
landscape="Default-Landscape-1366h@2x.png"

convert $portrait -resize 320x480 -gravity center -background white -extent 320x480 Default.png
convert $portrait -resize 640x960 -gravity center -background white -extent 640x960 Default@2x.png
convert $portrait -resize 1024x768 -gravity center -background white -extent 1024x768 Default-Landscape.png
convert $portrait -resize 2048x1536 -gravity center -background white -extent 2048x1536 Default-Landscape@2x.png
convert $portrait -resize 768x1024 -gravity center -background white -extent 768x1024 Default-Portrait.png
convert $portrait -resize 1536x2048 -gravity center -background white -extent 1536x2048 Default-Portrait@2x.png
convert $portrait -resize 1080x1920 -gravity center -background white -extent 1080x1920 Default-640h@3x.png
convert $landscape -resize 1920x1080 -gravity center -background white -extent 1920x1080 Default-Landscape-640h@3x.png
convert $portrait -resize 750x1334 -gravity center -background white -extent 750x1334 Default-667h@2x.png
convert $landscape -resize 1334x750 -gravity center -background white -extent 1334x750 Default-Landscape-667h@2x.png
convert $portrait -resize 640x1136 -gravity center -background white -extent 640x1136 Default-568h@2x.png
convert $landscape -resize 1136x640 -gravity center -background white -extent 1136x640 Default-Landscape-568h@2x.png
# convert $landscape -resize 2048x2732 -gravity center -background white -extent 2048x2732 Default-1366h@2x.png
# convert $landscape -resize 2732x2048 -gravity center -background white -extent 2732x2048 Default-Landscape-1366h@2x.png
convert $portrait -resize 1536x2048 -gravity center -background white -extent 1536x2048 Default-1024h@2x.png
convert $landscape -resize 2048x1536 -gravity center -background white -extent 2048x1536 Default-Landscape-1024h@2x.png


# **Splash Screens** | Portrait & Landscape, [iOS Human Interface Guidelines](https://developer.apple.com/ios/human-interface-guidelines/graphics/launch-screen/) | ![](assets/README-2dc5de66.png)
# Default (Portrait)|	320px by 480px | `Default.png`
# Default (Portrait)|	640px by 960px | `Default@2x.png`
# iPad |	1024px by 768px | `Default-Landscape.png`
# iPad Retina |	2048px by 1536px | `Default-Landscape@2x.png`
# iPad |	768px by 1024px | `Default-Portrait.png`
# iPad Retina |	1536px by 2048px | `Default-Portrait@2x.png`
# iPhone 6s Plus, iPhone 6 Plus |	1080px by 1920px | `Default-640h@3x.png`
# iPhone 6s Plus, iPhone 6 Plus |	1920px by 1080px | `Default-Landscape-640h@3x.png`
# iPhone 6s, iPhone 6 | 750px by 1334px | `Default-667h@2x.png`
# iPhone 6s, iPhone 6 | 1334px by 750px | `Default-Landscape-667h@2x.png`
# iPhone SE | 640px by 1136px | `Default-568h@2x.png`
# iPhone SE | 1136px by 640px | `Default-Landscape-568h@2x.png`
# 12.9-inch iPad Pro | 2048px by 2732px | `Default-1366h@2x.png`
# 12.9-inch iPad Pro | 2732px by 2048px | `Default-Landscape-1366h@2x.png`
# 9.7-inch iPad Pro, iPad Air 2, iPad mini 4, iPad mini 2 | 1536px by 2048px | `Default-1024h@2x.png`
# 9.7-inch iPad Pro, iPad Air 2, iPad mini 4, iPad mini 2 | 2048px by 1536px | `Default-Landscape-1024h@2x.png`