calculating total time of downloading data?

i am using apple's sample URLCache,but when i mention url, it loads data perfectly but i w开发者_高级运维ant to calculate time of downloading(till completion),is there anyh built in method?

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Add NSDate property to your class, name it,let's say, downloadStart and when download starts, save actual time to it - self.downloadStart = [NSDate date];

Then in -connectionDidFinishLoading: delegate method implementation do:

NSDate *downloadEnd = [NSDate date];
NSTimeInterval totalTime = ([downloadEnd timeIntervalSince1970] - [downloadStart timeIntervalSince1970]);

//Total time now contains number of seconds since download start time
NSLog(@"Download finished in %f seconds", totalTime);

self.downloadStart = nil;

That's it. Please note that the code above is just a kind of abstract how to do the trick, so don't use in copy & paste manner.