Simple way to get GMT date from ISO8601 date in Objective C

gistfile1.m

- (NSString *)getGMTDateStringfromISO8601DateString:(NSString *)ISODateString
{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ssZZZ"];
    
    ISODateString = [ISODateString stringByReplacingOccurrencesOfString:@":" withString:@"" options:0 range:NSMakeRange([ISODateString length]-5, 5)];
    NSDate *ISODate = [formatter dateFromString:ISODateString];
    
    [formatter setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"];
    [formatter setTimeZone:[NSTimeZone timeZoneWithAbbreviation:@"GMT"]];
    
    return [formatter stringFromDate:ISODate];
}