Age verification in Objective-C
Check this method. Pass value as minus 18 (-18)

-(NSDate *)offsetYear:(int)numOfYears date:(NSDate*)date {
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];
    [offsetComponents setYear:numOfYears];

    return [gregorian dateByAddingComponents:offsetComponents
                                  toDate:date options:0];
}