Which one is the best to use xcode?

edit: to remove personally identifying information not relevant to the thread.

The processor in the Mid-2011 Mac mini is twice as fast as the one in the Early 2009 (see the geekbench scores in the links below).
So the newer Mac mini has definitively an advantage over the older one.

For compiling code, a fast HD or better SSD helps of course, but when working in Xcode, you are probably on the critical path yourself (instead of your HD/SSD).

http://www.everymac.com/systems/app...i-core-2-duo-2.0-early-2009-nvidia-specs.html

http://www.everymac.com/systems/apple/mac_mini/specs/mac-mini-core-i5-2.3-mid-2011-specs.html

So go for the Mid-2011 Mac mini.

edit: to remove personally identifying information not relevant to the thread.

FWIW, I did a decent amount of iOS dev work [in Xcode] on a 2010 13" MBP C2D 2.4, 8GB RAM and an SSD which is close to your 2009 Mini spec (though it does have that extra clock, and a 320M GPU vs. the 9400). In fact, I started with the original OOTB specs (4GB, 250GB HDD) and even that wasn't all that bad.

Xcode (at least the version at the time, a couple of years ago), wasn't as much of a resource hog as you would think.

The SSD upgrade in that MBP was a major performance boost. In fact, that machine is my Wife's and it is still humming right along

I agree, that #2 machine has some mismatching specs, if it's a '12 machine, that's potentially a really good deal. FWIW, you might be able to fetch $30-35 for the 500GB drive and then go with a small SSD (like 64GB) - Kingston and SanDisk have drives in that capacity in the mid $40-ish range.

Get the one with an SSD, it does wonders. An SSD is an even bigger difference than a CPU upgrade. You can notice the difference between a obsolete 5400-RPM harddrive and a SSD in read world tests and results.