Mac Pro 3.1 for Xcode, coding or programming?
The machine itself is quite up to the task.

However, it is limited to El Capitan 10.11, so whilst you could use it for learning, to publish Apple usually require you have the very latest Xcode; which is incapable of being run on an older OS. For instance, Xcode 9 requires macOS 10.13.2 minimum.

If you can find the next model up - the 2009 4,1 can be upgraded by a Firmware hack to become a 5,1* &amp; then be capable of running at least Mojave.

*It can be hard to tell the difference between a true 5,1 &amp; upgraded 4,1 - but this is the giveaway...



A 'true' 5,1 would say 2010 or 2012. A non-upgraded 4,1 couldn't be running even Sierra, so this has to be an upgraded 4,1
I know this for sure - it's my machine ;-)

Additional note: Whichever you decide on, the first thing to do is add an SSD as boot drive. The difference in performance cannot be overstated. Recent versions of macOS expect you to be running from SSD.