CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();
//Write the code to calculate the time here
// do something
CFAbsoluteTime end = CFAbsoluteTimeGetCurrent();
NSLog(@"%f", end - start);
CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();
//Write the code to calculate the time here
// do something
CFAbsoluteTime end = CFAbsoluteTimeGetCurrent();
NSLog(@"%f", end - start);