Detect if build is triggered from SwiftUI Preview in Build Phases - Run Script

Question

Is there any way to detect if the build was triggered by the SwiftUI Preview from inside Build Phases - Run Script?

I'm using swiftlint with --fix --format, the problem is when I have the Preview open it sometimes triggers a build, which often changes the file while I'm typing, which then brings up the "keep changes/revert" dialog. Keeping the changes often leads Xcode to crash. Ideally, I'd like to do something like this:

if buildWasTriggeredBySwiftUIPreview then
    swiftlint
else 
    swiftlint --fix --format && swiftlint
fi

Does this answer your question? It seems like you can just check an environment variable. — Sweeper
– Sweeper, Commented Jan 19, 2024 at 8:57

fer0n · Accepted Answer · 2025-04-20 07:47:22Z

3

Update

This no longer works in xCode 16 (developer forum discussion). Detecting it during runtime can be achieved with this. That sadly doesn't help for the build phase, though:

let isXcodePreview = ProcessInfo.processInfo.environment["XCODE_RUNNING_FOR_PREVIEWS”] != nil

Previous Answer

Thanks to Sweeper, this works:

if [ "${ENABLE_PREVIEWS}" = "YES" ]; then 
    swiftlint
else 
    swiftlint --fix --format && swiftlint  
fi

edited Apr 20 at 7:47

answered Jan 19, 2024 at 9:33

fer0n

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Comments

Marwen Doukh · Accepted Answer · 2025-01-16 11:37:29Z

0

Do not forget to activate Legacy Previews:
"Editor > Canvas > Use Legacy Previews Execution"

answered Jan 16 at 11:37

Marwen Doukh

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2 Comments

fer0n Jan 17 at 13:03

Does the flag not work in Xcode 16 anymore with the default preview?

Marwen Doukh Jan 20 at 8:17

No , you can see more infos here : forums.developer.apple.com/forums/thread/761439

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