Code to measure EXACT execution time inside code on iPad or Phone?

Question

Is is any difference between using mach_absolute_time and the simple NSDate method explained by golden eagle below?

Here\'s an excellen

Answer 1

loop
  {
   NSDate *start = [NSDate date];

  // a considerable amount of difficult processing here
  // a considerable amount of difficult processing here
  // a considerable amount of difficult processing here

   NSDate *methodFinish = [NSDate date];
   NSTimeInterval executionTime = [methodFinish timeIntervalSinceDate:start];

   NSLog(@"Execution Time: %f", executionTime);
  }

Should work.