О, хорошо, отличный улов зул.
В таком случае я бы сделал:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setTimeStyle:NSDateFormatterShortStyle];
[dateFormatter setDateStyle:NSDateFormatterNoStyle];
double time = 0.27392;
double timeInSeconds = time*24*60*60; // 0.27392 * 24 = 6.57408 hours *60 for minutes * 60 for seconds
NSDate *date = [NSDate dateWithTimeIntervalSinceReferenceDate:timeInSeconds]; //Creates a date: 1 January 2001 6:34:27 AM, GMT
NSLog(@"Time: %@", [dateFormatter stringFromDate:date]);
[dateFormatter release];