Xcode 4 on MBA 2012 4 GB

Question comes up routinely...

Any current mac is more than capable of running Xcode - but it's rare that it will be the only app you'll be knee deep in...

Consider assets involved, and the simulators, and the docs and the browser connected to the Dev Centers and the image editors, text editors, video editors.....

In any case, max the physical ram (3rd party ram is dirt cheap) and ...think about at least one external monitor. And a fast hard drive.

Also note that 4.1 is obsolete. 4.1.1 is current. See Xcode Versions ~ iOS - As of 8.07.12

I don't suggest any MBP - you'll just end up turning it into a desktop and crying about the small screen.

Check the store for refurb'd minis - tremendous bang for the buck.

My suggestion is getting a (probably refurbished) MacBook Pro 15". If you want to keep the price low, you can always upgrade its ram, hdd,... for nearly no Money.

If money isn´t a Problem for you I can only recommend you a 15" Retina Pro, since you got a lot of space for your Code on this screen (in like 1920x1200 mode) especially if you are trying to compare two Files in Xcode. I decided to get one to replace my 13" 2010 MBA. It´s a Day and Night difference especially when using Xcode.

You need to Decide first:

Are you Planing to develop GL Games with loads of heavy content? Are you using Aperature (eats my RAM like chocolate)? Do you often work on Big Projects with many Files / Lines of Code? Would you not mind carrying a 2 kg Laptop with you and is the Price Suitable for you?

Get a Retina Pro. (or a Pro if the Price plays a big role)

Are you planning to work on smaller to medium Projects? Are you new to Programming? Do you appreciate a Small, light laptop?

Get a MacBook Air.

Little tip besides: If you plan to get an Air, get it with 8GB Ram in every Case. You´ll really need it, trust me.

What is your budget? How much could you spend?

And: Would you prefer having a Laptop or a Desktop?

For a long time my primary development machine was a 2007 MacBook. Now I have a 2011 13" MacBook Pro. I think it is fine. It has full screen an multiple desktops. It is also more upgradable than an Air.

I would recommend you to get a stock Mac Mini (lowest end $599) and upgrade it to 8 or 16GB ($52 for 8GB, $143 for 16GB) (Link) by yourself. That would be $650 for the Mac. Means you still got around $450 for a Display and $100 for a Keyboard and a Mouse.

As a Screen from my own experience I can recommend you a Dell. If you get a chance you should go into a Store and take a look at a Screen before buying it but here is (just an option) a 27" Dell Planar for $469: Link

As Keyboard I use an Apple Keyboard with Numeric Keypad: Link ($49)

and as mouse (to stay in budget) I recommend an Apple mouse for $49. Link

This would get you a pretty speedy Mac Mini with a good Processor and a huge (pretty high-res) screen and Mouse + Keyboard for just $1.219.
You could also sell the Original 2GB of RAM you got with your Mac Mini to get the deficit of $19 in. (Though I wouldn´t recommend you to do that.)

Optional to that you (could) get a 15" MacBook Pro (refurb.) with (only 1440x900) but a Quad-Core i7 for $1.359. Link.
They Key difference here is that the Pro has both a Quad Core Processor and a Graphics Card- it has also got the benefit of being able to be carried around anywhere you´d like and you would not be limited to only be able to write code when you are at home.