Resolved Help with Making a Clock in Objective-C Command Line Utility

faroZ06 · Aug 23, 2012

I'm playing around in Objective-C with a "foundation tool" (Objective-C command line utility) project in Xcode. At the end of my program, it's supposed to go to a clock that updates itself in the Terminal window. The problem is that it doesn't start on the right time, so it's almost always off by a fraction of a second. I tried to fix that by having it wait until the nanosecond time is a multiple of 10^9, but this ends up just going into infinite loop. What am I doing wrong, and is there a better way (I'm guessing there is)?

Quote

double nano = 1111111111111;
while (fmod(nano, 1000000000) != 0){
nano = [NSDate timeIntervalSinceReferenceDate];
} //This while loop waits for the nanoseconds to be divisible by 10^9.
while (true){
formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat"dd-MM-yyyy HH:mm:ss"];

dateString = [formatter stringFromDate:[NSDate date]];
printf([dateString UTF8String]); printf("\n");
sleep(1); // or usleep(3000000);
system("clear");
}
Click to expand...

gnasher729 · Aug 23, 2012

faroZ06 said: ↑

I'm playing around in Objective-C with a "foundation tool" (Objective-C command line utility) project in Xcode. At the end of my program, it's supposed to go to a clock that updates itself in the Terminal window. The problem is that it doesn't start on the right time, so it's almost always off by a fraction of a second. I tried to fix that by having it wait until the nanosecond time is a multiple of 10^9, but this ends up just going into infinite loop. What am I doing wrong, and is there a better way (I'm guessing there is)?
Click to expand...

[NSDate timeIntervalSinceReferenceDate] measures the time interval in seconds.

And to avoid wasting CPU time, call [NSDate timeIntervalSinceReferenceDate] once, round up to the next second by calling ceil (), then call usleep for waiting the right amount of time.

faroZ06 · Aug 23, 2012

gnasher729 said: ↑

[NSDate timeIntervalSinceReferenceDate] measures the time interval in seconds.

And to avoid wasting CPU time, call [NSDate timeIntervalSinceReferenceDate] once, round up to the next second by calling ceil (), then call usleep for waiting the right amount of time.
Click to expand...

Ah, thanks. Sorry for the noob question.

gnasher729 · Aug 23, 2012

faroZ06 said: ↑

Ah, thanks. Sorry for the noob question.
Click to expand...

Nothing to be sorry about. You posted the code that caused the problem, which means you gave the information that was needed to find the cause of the problem - that puts you far ahead of the average.

Resolved Help with Making a Clock in Objective-C Command Line Utility

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Resolved Help with Making a Clock in Objective-C Command Line Utility

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