Attempt at using the iOS private `GSEventVibrateForDuration` function... this doesn't seem to work...

vib.c

// To compile:
//   gcc -o vib vib.c -F/System/Library/PrivateFrameworks -framework GraphicsServices
#import <GraphicsServices/GSEvent.h>

int main() {
  GSEventVibrateForDuration(3.5f);
  sleep(3500);
  return 0;
}