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Comment by jonnynezbo | Hacker News Reader

+1 for mentioning the "Clean Build Folder" issue. I was stuck on that for about an hour yesterday, then I found this post:

http://stackoverflow.com/questions/32586144/upgraded-to-swif...

I didn't know about using the Alt key to reveal "Clean Build Folder", and I've been doing iOS dev for years. I'll add this to the list of unhelpful compile errors that are fixed by cleaning the build.

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"Clean Build Folder" is basically the "turn it off, then turn it back on" of Xcode. Almost anytime you get a weird compiler error on a project that compiled fine moments ago, it's solved by "Clean Build Folder."

Definitely a good trick to know.

Or for those who prefer automating, add this to ~/.bash_profile:

   alias nuke="rm -rf ~/Library/Developer/Xcode/DerivedData/"

That's pretty drastic. That nukes the derived data folder of all your Xcode projects. If you work on more than 1, using this to solve a problem in 1 will lead to needing to rebuild all of your projects. That seems a bit extreme for an issue in a single project.

I always advice people to put their DerivedData and build folder somewhere accessible. You can change it settings, don't use the default setting.

Good tip. As someone with quite a small main HDD I'll do this ASAP.

cmd+shift+k followed by cmd+alt+shift+k is a multiple-times-a-day incantation for me :)

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