title: Can I trust Cocoa APIs not to fail silently, or do I have to defensively check everything?
body: <p>Coming from a Symbian background, I'm somewhat concerned about the seeming lack of error handling in Cocoa.  Cocoa has many methods that, as far as I can see, have no error reporting and yet could fail.</p>
  
  <p>Eg How come NSMutableString appendString has a void return type and doesn't throw exceptions (at least the <a href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/nsmutablestring_Class/Reference/Reference.html#//apple_ref/occ/instm/NSMutableString/appendString:" rel="nofollow noreferrer" title="NSMutableString appendString">documentation</a> doesn't mention any)? Surely if I append a long enough string then theoretically I could run out of memory.  Is it paranoid of me to check the length of the NSMutableString before and after appending to verify that the append worked?</p>