Alternatives to type casting when formatting NS(U)Integer on 32 and 64 bit architectures?

From http://pubs.opengroup.org/onlinepubs/009695399/functions/printf.html:

• z
  Specifies that a following [...] conversion specifier applies to a size_t or the corresponding signed integer type argument;
• t
  Specifies that a following [...] conversion specifier applies to a ptrdiff_t or the corresponding unsigned type argument;

And from http://en.wikipedia.org/wiki/Size_t#Size_and_pointer_difference_types:

• size_t is used to represent the size of any object (including arrays) in the particular implementation. It is used as the return type of the sizeof operator.
• ptrdiff_t is used to represent the difference between pointers.

On the current OS X and iOS platforms we have

typedef __SIZE_TYPE__ size_t;typedef __PTRDIFF_TYPE__ ptrdiff_t;

where __SIZE_TYPE__ and __PTRDIFF_TYPE__ are predefined by thecompiler. For 32-bit the compiler defines

#define __SIZE_TYPE__ long unsigned int#define __PTRDIFF_TYPE__ int

and for 64-bit the compiler defines

#define __SIZE_TYPE__ long unsigned int#define __PTRDIFF_TYPE__ long int

(This may have changed between Xcode versions. Motivated by @user102008's comment, I have checked this with Xcode 6.2 and updated the answer.)

So ptrdiff_t and NSInteger are both typedef'd to the same type:int on 32-bit and long on 64-bit. Therefore

NSLog(@"%td", i);NSLog(@"%tu", u);

work correctly and compile without warnings on all currentiOS and OS X platforms.

size_t and NSUInteger have the same size on all platforms, butthey are not the same type, so

NSLog(@"%zu", u);

actually gives a warning when compiling for 32-bit.

But this relation is not fixed in any standard (as far as I know), therefore I wouldnot consider it safe (in the same sense as assuming that long has the same sizeas a pointer is not considered safe). It might break in the future.

The only alternative to type casting that I know of is from the answer to "Foundation types when compiling for arm64 and 32-bit architecture", using preprocessor macros:

// In your prefix header or something#if __LP64__#define NSI "ld"#define NSU "lu"#else#define NSI "d"#define NSU "u"#endifNSLog(@"i=%"NSI, i);NSLog(@"u=%"NSU, u);

I prefer to just use an NSNumber instead:

NSInteger myInteger = 3;NSLog(@"%@", @(myInteger));

This does not work in all situations, but I've replaced most of my NS(U)Integer formatting with the above.

According to Building 32-bit Like 64-bit, another solution is to define the NS_BUILD_32_LIKE_64 macro, and then you can simply use the %ld and %lu specifiers with NSInteger and NSUInteger without casting and without warnings.