XCode 13.3's new ability for you to enable XCBuild and use more cores for faster build times is quite impressive. The build times are incredibly fast and it's not a small difference between how it used it to be.
That being said, there seems to be a major bug with this feature. While building within XCode and running in Simulator works fine, building on a real device while this feature is enabled does not. The build succeeds but an error message appears in XCode stating your iPhone is busy and it's downloading symbols. Very strange.
So, if you want to use this new feature, here's how you do it:
- Open terminal
- defaults write com.apple.dt.XCBuild EnableSwiftBuildSystemIntegration 1
You can verify that it worked by typing: defaults read com.apple.dt.XCBuild
However, if you need to build to a real device and are receiving strange errors, you need to disable this feature like this:
- Open terminal
- defaults write com.apple.dt.XCBuild EnableSwiftBuildSystemIntegration 0
Hopefully Apple will resolve this issue in the next update as it would be really amazing to have super fast build times, even when building to a real device.