How to decrease build times / speed up compile time in Xcode?

Question

What strategies can be used in general to decrease build times for any Xcode project? I\'m mostly interested in Xcode specific strategies.

I\'m doi

Answer 1

I used a script to make use of a RAM drive, together with some "forward declarations" optimizations my project clean build time went from 53 seconds to 20 seconds.

I was tempted to get the Gui on the AppStore, but opted rather to go for command line. I put the script as part of git repository.

To see the build times, enter this in a terminal: "defaults write com.apple.dt.Xcode ShowBuildOperationDuration YES"

Restart Xcode to notice the build times in the toolbar. (this is my non clean build time using objective-c)

Adjust the script to your liking. - Note the script clears the derived data folder.

#!/bin/sh

#2 GIG RAM
GIGA_BYTES=$((2*1024*1024*1024))

# a sector is 512 bytes
NUMSECTORS=$((${GIGA_BYTES}/512))

#ram disk
mydev=`hdiutil attach -nomount ram://$NUMSECTORS`
newfs_hfs $mydev

# make mount point
MOUNT_POINT=/Users/your_user_name/Library/Developer/Xcode/DerivedData

# ******************************************* 
# ** WARNING - MOUNT POINT WILL BE DELETED ** 
# *******************************************
rm -rf ${MOUNT_POINT}
mkdir -p ${MOUNT_POINT}

# mount
mount -t hfs $mydev ${MOUNT_POINT}
echo unmount $(MOUNT_POINT)

To see the effect and to control the RAM Drive:

mount                       - see mount points
umount mount_point          - unmount point
diskutil list               - see disks
diskutil eject /dev/diskX   - eject the disk
df -ahl                     - see free space

NOTE: I essentially use the hdiutil provided by macOs. I tried switching the -kernel option (no swapping to disk) on but failed on my machine, saying it is not implemented.

Maybe the new OS coming soon we will see even more improvements as the new file system copy feature is really fast, and possibly makes this script redundant.