NSUInteger vs NSInteger, int vs unsigned, and similar cases

Question

Anyone have the expertise to explain when to use NSUInteger and when to use NSInteger?

I had seen Cocoa methods returning NSInteger even in cases where the returned

Answer 1

You should also be aware of integer conversion rules when dealing with NSUInteger vs. NSInteger:

The following fragment for example returns 0 (false) although you'd expect it to print 1 (true):

NSInteger si = -1;
NSUInteger ui = 1;
printf("%d\n", si < ui);

The reason is that the [si] variable is being implicitly converted to an unsigned int!

See CERT's Secure Coding site for an in-depth discussion around these 'issues' and how to solve them.