It’s a folder containing your build information, targets of debug and release as well as projects index.
Why do we delete the derived data ?
It helps to get rid of some code compilations issues, slow project and constant reindexing issue.
Open Xcode and choose Preferences
Select 'Locations' tab.
As shown below, you can click on the arrow to find the derived data folder.
You can see a folder 'Derived Data' Right click and Delete folder.