Mac mini 2012 (2.3 quad core) Vs late 2014 (2.8 dual core) I'm on my way to buy my new mac mini for my IOS development and I'm a bit unfamiliar with Apple products so I just want an advice from experts about that.

my budget is not that high so I have 2 options and need to know which the best i can buy for IOS development :

1) used Mac mini 2.3 quad core 16 GB of RAM with HDD 5400 1 TB (But it almost used for a year)
2) New Mac mini 2.8 dual core 8 GB of RAM with 1TB fusion drive.

Both are the same price and I'm a bit lost to decide. Any help would be much appreciated !!
Go with the older model.

The quad core i7 can run circles around the dual core i5 in multithreaded applications, which Xcode is (especially for code compilation tasks). You've seen that on the Geekbench scores.

The hard drive's speed is not really going to make much of an impact on your intended use.

The graphics chip is completely irrelevant.

The additional RAM will be a big boost especially running Yosemite.