Creates a ramdisk and start Xcode with the DerivedData stored in ramdisk. Also deletes the ramdisk and reset Xcode prefs.

xc_ramdisk.sh

#!/bin/bash

# Creates a ramdisk and start Xcode with the DerivedData stored in ramdisk. Also deletes the ramdisk and reset Xcode prefs.
# xc_ramdisk.sh
# - creates a ramdisk, set Xcode DerivedData to this disk and start Xcode.
# - umount a ramdisk, set Xcode DerivedData to default
# Stephan Burlot, Coriolis Technologies, http://www.coriolis.ch
#
# based on Alex Shevchenko xcode_ramdisk.sh script (https://gist.github.com/skeeet/2367298)
# based on Diego Freniche xc-launch.sh script (https://github.com/dfreniche/xc-launch)

# mount point for the ramdisk volume
ramdisk='/Volumes/ramdisk'
# size of created disk in M-bytes
disk_size=1024

# compute the size of the disk in 512-byte sectors
rdsize=$(($disk_size*1024*1024/512))

StartService () {
	cmd="\$3 == \"$ramdisk\" {print \$3}"
	if [[ $(mount | awk "$cmd") != "" ]]; then
		echo "$ramdisk is already mounted, erasing ramdisk."
		rm -rf /Volumes/ramdisk
	else
		diskutil erasevolume HFS+ "ramdisk" `hdiutil attach -nomount ram://$rdsize`
	fi

	# set the Derived Data folder in Xcode prefs
	/usr/bin/defaults write com.apple.dt.Xcode IDECustomDerivedDataLocation "$ramdisk"
	open -a Xcode
}

StopService () {
	if [ -z "$(pgrep Xcode)" ]; then
		cmd="\$3 == \"$ramdisk\" {print \$3}"
		if [[ $(mount | awk "$cmd") != "" ]]; then
			# reset the Derived Data folder in Xcode prefs to default
			/usr/bin/defaults delete com.apple.dt.Xcode IDECustomDerivedDataLocation
			# eject disk
			hdiutil detach $ramdisk
		else
			echo "$ramdisk is not mounted"
		fi
	else
		echo "Xcode is running, nothing done."
	fi
}

RestartService () {
	ConsoleMessage "Restarting, nothing will be done here..."
}

# Test for arguments.
if [ -z $1 ]; then
	echo "Usage: $0 [start|stop] "
	exit 1
fi

# Source the common setup functions for startup scripts
test -r /etc/rc.common || exit 1 
. /etc/rc.common

RunService "$1"

works like a charm~ thanks so much 😄