Finding Swift really buggy atm - where XCode, Swift Compiler and SourceCode service routinely crashes multiple times a day for me. A lot of my time is spent sympathizing with the compiler and getting hit with hard fought lessons on what things to avoid - basically don't step too far outside the Swift Programming Guide. Apple's also glacially slow at responding to bug reports - I'm keenly waiting on the next Q/A release of XCode/Swift.
Dogfooding usually implies that the technology is used in mainline business operations. It needs to be more than building a demo, it needs to provide sustenance.
There's a whole repo dedicated to Swift compiler crashes being maintained at: https://github.com/practicalswift/swift-compiler-crashes