FYI, It took me a full day to convert 10,000 lines of Swift 1.2 to Swift 2, after the auto conversion ran. As with any recent Beta, I have experienced a number of problems, the most annoying being the inability to reliabily run in simulator. It seems that I have to run from xcode, then it fails to connect. So I then go to the simulator and run the program manually, kill it and run it again manually (usually it kills itself the first time), then once I have it running manually, kill it, then run it from Xcode. And yes, I also get lots of stuff in the log that seems less than desirable. Lets hope that there are a bunch of stored up fixes just waiting for everyone to get back from WWDC.