Xcode on Mac App Store can't install , show disk space not enough

Question

I\'m using the Mac OS to install the XCode10.1.

I have 18.43GB free disk space in the mac,

but when I click the install button on the Xcode from the app store,<

Answer 1

in my MacBook had 31 GB available (14 GB purgeable), macOS 10.14.5 still said it had not enough free space to complete my purchase of Xcode 10.2, just deleted directory ~/Library/Caches/storedownloadd, started downloading.