Install Xcode SDK major releases from Xcode 6.1.1 - 7.2.1 into a host's Xcode.app

install_xcodes.bash

#!/usr/bin/env bash

PREFIX='./xcodes'
  DMGs=(xcode_6.1.1.dmg
        Xcode_6.2.dmg
        Xcode_6.3.2.dmg
        Xcode_6.4.dmg
        Xcode_7.0.1.dmg
        Xcode_7.1.1.dmg
        Xcode_7.2.1.dmg)

# DISCLAIMER: These are not official checksums from Apple,
# just ones I've generated from my dropbox copy of the DMGs.
url_611="https://www.dropbox.com/s/f0fgbj43wbgmukh/xcode_6.1.1.dmg?dl=0"
md5_611="00773faa3ddc9a0b7b94bab8496aa522"
url_62="https://www.dropbox.com/s/kv711z3c2x76vvw/Xcode_6.2.dmg?dl=0"
md5_62="fe4c6c99182668cf14bfa5703bedeed6"
url_632="https://www.dropbox.com/s/amnisaibwfpr6jw/Xcode_6.3.2.dmg?dl=0"
md5_632="a61d18cc7abf5de83f24ae7dc4ee281a"
url_64="https://www.dropbox.com/s/m8pq8rfgz3y58d9/Xcode_6.4.dmg?dl=0"
md5_64="fc57760b91df8d45ee57ba80436e49a9"
url_701="https://www.dropbox.com/s/xiqafaa99wkwxr7/Xcode_7.0.1.dmg?dl=0"
md5_701="3702b5291ed8127781158eb6a79d03cb"
url_711="https://www.dropbox.com/s/cwpsd42f57szcsw/Xcode_7.1.1.dmg?dl=0"
md5_711="25e4af4f0a0251e08446cd51485041f1"
url_721="https://www.dropbox.com/s/6gsm40zdt9i519k/Xcode_7.2.1.dmg?dl=0"
md5_721="e9c6ec03fd269cb2802180800fb7fb0e"

#
# preflight()
#
# Make sure we have an Xcode.app on the host and all the DMGs
# we are expecting before we do any heavy lifting.
#
function preflight() {
  echo "INFO: Starting preflight check."

  # is first xcode installed?
  if [ -d "/Applications/Xcode.app" ]; then
    # do you have all the DMGs?
    declare -a missing
    for dmg in "${DMGs[@]}"; do
      if [ ! -s "${PREFIX}/${dmg}" ]; then
        missing=(${missing[@]} $dmg)
      fi
    done
    if [[ ! -z ${missing[@]} ]]; then
      echo "ERR: Preflight check failed: Missing some DMGs"
      echo "ERR: Missing: ${missing[@]}"
      exit 255
    fi
  else
    echo "ERR: Preflight check failed: No base Xcode detected."
    echo "ERR: Please install the most recent Xcode via the App Store."
    exit 256
  fi

  echo "INFO: Preflight check passed!"
}

#
# main()
#
# Where all the pieces come together except the preflight check.
#
function main() {
  attach-all

  copy-all "iPhoneOS"
  copy-all "iPhoneSimulator"

  detach-all
}

#
# copy-all()
#
# Given a platform ("iPhoneOS", "AppleTVOS", etc.) copy all
# the files from that Xcode's version into the host's Xcode.app.
#
# Also renames the host's Xcode.app's version of said platform
# SDK and removes the symlinking to the latest version.
#
function copy-all() {

  if [ -z "${@}" ]; then
    echo "ERR: Which SDK to consolidate not specified."
    exit 255
  fi

  platform="$1"
  base="/Applications/Xcode.app/Contents/Developer/Platforms/${platform}.platform/Developer/SDKs"

  echo "INFO: Removing latest symlink and moving original into place."
  sym="$(find ${base} -type l -maxdepth 1)"
  name="${sym##*/}"
  sudo rm -rfv $sym
  sudo mv -v "${base}/${platform}.sdk" "${sym}"

  echo "INFO: Copying ${platform} SDKs"
  for SDK in /Volumes/dmg.*/Xcode.app/Contents/Developer/Platforms/${platform}*/Developer/SDKs/${platform}*[0-9]*.sdk; do
    name="${SDK##*/}"
    real="${SDK%%${platform}[0-9]*}${platform}.sdk"

    sudo rsync -a --ignore-existing "$real" "${base}/${name}" &
  done

  for pid in $(jobs -p); do
    wait $pid
  done
  echo
}

#
# attach()
#
# Attach a single .DMG file to a path matching the pattern:
# /Volumes/dmg.[a-zA-Z0-9]{6} (per the "-mountrandom" flag).
# Close any resultant Finder.app windows with the title "Xcode."
#
# Does not handle EULAs. Will verify if DMG specified is
# already attached, but will not attach duplicates of the
# same DMG.
#
function attach() {
  dmg="${PREFIX}/$1"
  path="$(hdiutil attach "${dmg}" -mountrandom "/Volumes" | grep Volumes | awk '{ print substr($0, index($0,$3)) }')"
  while ( ( osascript -e 'tell application "Finder" to close Finder window "Xcode"' 2>&1 ) > /dev/null ); do
    sleep 1
  done
  echo "$path"
}

#
# attach-all()
#
# Loop through $DMGs and attach() each.
#
function attach-all() {
  for dmg in "${DMGs[@]}"; do
    path="$(attach "$dmg")"
    version="${dmg//[^0-9.]}"
    version="${version%%.}"
    echo -e "${dmg} (${version})\t:\t${path}"
  done
}

#
# detach()
#
# Detach a single attached volume specified by path.
#
function detach() {
  path="$1"
  echo "INFO: Detaching ${path}..."
  if (hdiutil detach "$path" 2>&1 > /dev/null); then
    echo "INFO: Success!"
  else
    echo "ERR: Failure. :("
  fi
}

#
# detach-all()
#
# Detach all attached volumes that resemble the pattern:
# /Volumes/dmg.[a-zA-Z0-9]{6}
#
function detach-all() {
  echo "INFO: Detaching all Xcode DMGs from /Volumes/dmg.*"
  for dmg in /Volumes/dmg.*; do
    detach "$dmg"
  done
}

preflight
main