Objective-C Language NSInteger and NSUInteger


The NSInteger is just a typedef for either an int or a long depending on the architecture. The same goes for a NSUInteger which is a typedef for the unsigned variants. If you check the NSInteger you will see the following:

typedef long NSInteger;
typedef unsigned long NSUInteger;
typedef int NSInteger;
typedef unsigned int NSUInteger;

The difference between an signed and an unsigned int or long is that a signed int or long can contain negative values. The range of the int is -2 147 483 648 to 2 147 483 647 while the unsigned int has a range of 0 to 4 294 967 295. The value is doubled because the first bit isn't used anymore to say the value is negative or not. For a long and NSInteger on 64-bit architectures, the range is much wider.

Most methods Apple provides are returning an NS(U)Integer over the normal int. You'll get a warning if you try to cast it to a normal int because you will lose precision if you are running on a 64-bit architecture. Not that it would matter in most cases, but it is easier to use NS(U)Integer. For example, the count method on a array will return an NSUInteger.

NSNumber *iAmNumber = @0;

NSInteger iAmSigned = [iAmNumber integerValue];
NSUInteger iAmUnsigned = [iAmNumber unsignedIntegerValue];

NSLog(@"%ld", iAmSigned); // The way to print a NSInteger.
NSLog(@"%lu", iAmUnsigned); // The way to print a NSUInteger.

Just like a BOOL, the NS(U)Integer is a primitive datatype, so you sometimes need to wrap it in a NSNumber you can use the @ before the integer to cast it like above and retrieve it using the methods below. But to cast it to NSNumber, you could also use the following methods:

[NSNumber numberWithInteger:0];
[NSNumber numberWithUnsignedInteger:0];