The short answer
Yes. Rebuilt or re-downloaded automatically when needed.
What is it?
Xcode Previews run on their own set of hidden simulators, separate from the ones you see in Xcode’s device list. This folder holds those preview devices and the builds and data Xcode puts on them. It grows with each new SDK and platform you preview on and often reaches several gigabytes.
What happens if you delete it?
Xcode recreates the preview simulators the next time you open a canvas, so the first preview after removal takes longer to appear. Your preview code is untouched.
How to remove it properly
Quit Xcode, then run xcrun simctl --set previews delete all in Terminal, which deletes all preview simulators with Apple’s own tool (permanent). Alternatively, move ~/Library/Developer/Xcode/UserData/Previews to the Trash with Finder’s Go › Go to Folder….
Quit the app that uses it, then move it to the Trash. Empty the Trash when you’re sure.
How MoreRoom helps
MoreRoom recognises this item, shows its real size and when it was last used, and labels it “Safe to remove”. In the free version you can move it to the Trash in one click, with Undo; Pro collects every safe item at once.
Frequently asked questions
Is it safe to delete Xcode’s SwiftUI Previews folder?
Yes. Rebuilt or re-downloaded automatically when needed. Xcode recreates the preview simulators the next time you open a canvas, so the first preview after removal takes longer to appear. Your preview code is untouched.
Will SwiftUI preview data come back after I delete it?
Yes. Xcode recreates the preview simulators the next time you open a canvas, so the first preview after removal takes longer to appear. Your preview code is untouched.
How do I remove SwiftUI preview data properly?
Quit Xcode, then run xcrun simctl --set previews delete all in Terminal, which deletes all preview simulators with Apple’s own tool (permanent). Alternatively, move ~/Library/Developer/Xcode/UserData/Previews to the Trash with Finder’s Go › Go to Folder….