Hello, Looking for the cheapest bare minimum laptop for iOS development. What specs would you say are needed? I'm just learning how to program so I just want to test it out first. Was looking for a 13" screen. Also, someone was telling me you can't replace the battery on some macs as they are soldered in place? That would be my only concern with buying used is that it would have horrible battery life and I would not be able to change it out easily. Budget would be sub $600. Is the latest Mac OS required?