How to parse an ISO-8601 duration in Objective C?

Question

I\'m looking for an easy way to parse a string that contains an ISO-8601 duration in Objective C. The result should be something usable like a NSTimeI

Answer 1

slightly modifying function of the user

Sergei Pekar

+ (NSString*)parseISO8601Time:(NSString*)duration
{
    NSInteger hours = 0;
    NSInteger minutes = 0;
    NSInteger seconds = 0;

    //Get Time part from ISO 8601 formatted duration http://en.wikipedia.org/wiki/ISO_8601#Durations
    if ([duration rangeOfString:@"T"].location == NSNotFound || [duration rangeOfString:@"P"].location == NSNotFound) {
        NSLog(@"Time is not a part from ISO 8601 formatted duration");
        return @"0:00 Error";
    }

    duration = [duration substringFromIndex:[duration rangeOfString:@"T"].location];

    while ([duration length] > 1) { //only one letter remains after parsing
        duration = [duration substringFromIndex:1];

        NSScanner *scanner = [[NSScanner alloc] initWithString:duration];
        NSString *durationPart = [[NSString alloc] init];
        [scanner scanCharactersFromSet:[NSCharacterSet characterSetWithCharactersInString:@"0123456789"] intoString:&durationPart];

        NSRange rangeOfDurationPart = [duration rangeOfString:durationPart];

        if ((rangeOfDurationPart.location + rangeOfDurationPart.length) > duration.length) {
            NSLog(@"Time is not a part from ISO 8601 formatted duration");
            return @"0:00 Error";
        }

        duration = [duration substringFromIndex:rangeOfDurationPart.location + rangeOfDurationPart.length];

        if ([[duration substringToIndex:1] isEqualToString:@"H"]) {
            hours = [durationPart intValue];
        }
        if ([[duration substringToIndex:1] isEqualToString:@"M"]) {
            minutes = [durationPart intValue];
        }
        if ([[duration substringToIndex:1] isEqualToString:@"S"]) {
            seconds = [durationPart intValue];
        }
    }

    if (hours != 0)
        return [NSString stringWithFormat:@"%ld:%02ld:%02ld", (long)hours, (long)minutes, (long)seconds];
    else
        return [NSString stringWithFormat:@"%ld:%02ld", (long)minutes, (long)seconds];
}