macOS tmp program

[jamesapp]

working on a program from a book by Stephen G. Kochan
here is the program which i called prog16.5.m

// some basic path operations

#import <Foundation/NSString.h>
#import <Foundation/NSArray.h>
#import <Foundation/NSFileManager.h>
#import <Foundation/NSAutoreleasePool.h>
#import <Foundation/NSPathUtilities.h>
#import <stdio.h>

int main (int argc, char *argv[])
{
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
  NSString *fName = @"path.m";
  NSFileManager *NSFm;
  NSString *path, *tempdir, *extension, *homedir, *fullpath;
  NSString *upath = @"~stevekochan/progs/../ch16/./path.m";
  NSArray *components;
  int i, n;
  
  NSFm = [NSFileManager defaultManager];
  
  //get the temporary working directory
  
  tempdir = NSTemporaryDirectory ();
  
  printf ("Temporary Directory is %s\n", [tempdir UTF8String]);
  
  // extract the base directory from current directory
  
  path = [NSFm currentDirectoryPath];
  printf ("Base dir is %s\n", [[path lastPathComponent] UTF8String]);
  
  //create a full path to the file fName in current directory
  
  fullpath = [path stringByAppendingPathComponent: fName];
  printf ("fullpath to %s is %s\n", [fName UTF8String], [fullpath UTF8String]);
  
  // get the file name extension
  
  extension = [fullpath pathExtension];
  printf ("extension for %s is %s\n", [fullpath UTF8String],
        [extension UTF8String]);
        
   // get user's home directory
   
   homedir = NSHomeDirectory ();
   printf ("Your home directory is %s\n", [homedir UTF8String]);
   
   // divide a path into its components
   
   components = [homedir pathComponents];
   
   n = [components count];
   
   for (i = 0; i < n; ++i)
        printf (" %s\n", [[components objectAtIndex: i] UTF8String]);
        
    // "standardize" a path
    
    printf ("%s => %s\n", [upath UTF8String],
                [[upath stringByStandardizingPath] UTF8String]);
                
    [pool release];
    return 0;
}

here is the output from the book:

Temporary Directory is /tmp
Base dir is ch16
fullpath to path.m is /Users/stevekochan/mysrc/ch16/path.m
extension for /Users/stevekochan/mysrc/ch16/path.m is m
Your home directory is /Users/stevekochan
     /
     Users
     stevekochan
~stevekochan/progs/../ch16/./path.m => /Users/stevekochan/ch16/path.m

and the output i got

james-collinss-macbook-pro:prog16 jamescollins$ ./prog16.5
Temporary Directory is /var/folders/Sh/ShzETZejFJOmnWAK-et4WE+++TI/-Tmp-/
Base dir is prog16
fullpath to path.m is /Users/jamescollins/objcee/prog16/path.m
extension for /Users/jamescollins/objcee/prog16/path.m is m
Your home directory is /Users/jamescollins
 /
 Users
 jamescollins
~stevekochan/progs/../ch16/./path.m => ~stevekochan/ch16/path.m

the program seemed to compile and run ok.
just wondering about the logic behind this program like,
in the program the lines where it says:

NSString *upath = @"~stevekochan/progs/../ch16/./path.m";

i thought of replacing @"~stevekochan with my home directory like,
@"~jamescollins
also the temporary dir, is this a directory that the program created?
why didn't my program create the temporary dir in /Tmp?
any help would be appreciated.