title: Efficiency NSString vs NSInteger/int - only for textual representation
body: <p>I'd like to know if it would make any sense to cast/convert a number, parsed from a csv file, e.g. customer id, to a NSString?
  Or maybe better a simple int? As I'm quite new to obj-c, I'm not really sure, wether to consistently use the NSxyz types, or use what I'm used to, coming from Java/C/C++.</p>
  
  <p>Actually the value only is stored in a variable, and then loaded into some textfields (which again would imply a conversion back to NSString I guess?).</p>
  
  <p>Would there be any benefit in less memory being used? Let's assume the ids had 6 digits, parsing roughly 10'000-100'000 customers. Same would apply to smaller numbers, e.g. the addresses street number.</p>