iPhone设备生成

我有以下代码

@implementation UIDevice(machine)

- (NSString *)machine
{
  size_t size;

  // Set 'oldp' parameter to NULL to get the size of the data
  // returned so we can allocate appropriate amount of space
  sysctlbyname("hw.machine", NULL, &size, NULL, 0); 

  // Allocate the space to store name
  char *name = malloc(size);

  // Get the platform name
  sysctlbyname("hw.machine", name, &size, NULL, 0);

  // Place name into a string
  NSString *machine = [NSString stringWithCString:name];

  // Done with this
  free(name);

  return machine;
}

@end

/* ... */

NSLog(@"device: %@", [[UIDevice currentDevice] machine]);

我得到的输出为:

Platforms:
-----------
iPhone1,1 
iPhone1,2 
iPod1,1   
iPod2,1   

在iPhone/iPod touch后面附加的两个数字表示什么,即(1,1)、(1,2)等?

谢谢 比兰奇