(Working in Xcode 11 and 12)

You can go to File > Workspace Settings if you are in a workspace environment or File > Project Settings for a regular project environment.

Then click over the little grey arrow under Derived data section and select your project folder to delete it.

The simplest and fastest way is the following (if you have not changed the defaults folder for DerivedData).

Open terminal and past the following:

rm -rf ~/Library/Developer/Xcode/DerivedData

In Xcode 8, all the derived data is automatically cleaned. If you want to do it by hand, go to Locations tab from the Preferences, locate project's derived data folder, and delete files related to the project.

In macOS 10.12 and later, Xcode cleans up stale derived data, precompiled headers, and module caches. (23282174)

Xcode 8.0 Release Notes

Credits to @charmingToad

But from what I observed, the same behaviour is typical when using Xcode 8 on OS X 10.11.5/6

Go to Xcode -> Project Settings

You can find the way to go to derived Data

Method 1:

• Close Xcode

• Open Terminal and enter this command

  rm -rf ~/Library/Developer/Xcode/DerivedData
  

Method 2:

• Click on Xcode menu
• Go to Preference
• Select Locations (as shown in image)
• Click on the arrow below the Derived Data (as shown in image).

It will bring you to the location of derived data and you can just delete it manually.

Manual removal of derived data

If you want to remove derived data manually just run:

rm -rf ~/Library/Developer/Xcode/DerivedData

If you want to free up more disk space there's a few other directories you might want to clear out as well though.

Automatic removal of Xcode generated files

I have created a Bash script for removing all kinds of files generated by Xcode. Removing DerivedData content can be done by running:

./xcode-clean.sh -d

More info at

In your terminal :

rm -rf ~/Library/Developer/Xcode/DerivedData

In the Latest Xcode version 12+ Follow the below steps, I found here

1.

2.

It will navigate to the Derived Data folder then you can remove the content of the folder.

Select Xcode and Follow 4 steps that highlighted in photo and remove derived data then restart your project.

Another way to go to your derived data folder is by right click on your App under "Products" folder in xcode and click "Show in Finder".

Go to the root of the project using terminal and then paste the below mentioned line

rm -rf ~/Library/Developer/Xcode/DerivedData

Once it is executed, you can verify by going to Xcode > Preference > Locations -> Tap arrow shows ["DeriveData"] end point.

Steps For Delete DerivedData:

1. Open Finder
2. From menu click on Go > Go to Folder
3. Enter ~/Library/Developer/Xcode/DerivedData in textfield
4. Click on Go button
5. You will see the folders of your Xcode projects
6. Delete the folders of projects, which you don't need.

I've created a bash command. Configure it with 3 simple steps. then in the terminal just type cleandd

It may differ between versions of xcodes. Best approach is to go xcode preference page and from tab "Locations", directly open "Derived Data" directory.

DevCleaner on the Mac App Store did the trick for me!

Also looks useful for removing other cruft due to Xcode. Remember this is a 3rd party app so usual trust warnings apply.