NSDate *startOfMonth;
    NSDate *endOfMonth;
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDate *now = [NSDate date];
    NSTimeInterval interval;

    [cal rangeOfUnit:NSMonthCalendarUnit startDate:&startOfMonth interval:&interval forDate:now];
    endOfMonth = [startOfMonth dateByAddingTimeInterval:interval-1];
    NSLog(@"nnstartOfMonth: %@nendOfMonth: %@ninterval: %d",startOfMonth, endOfMonth, (int)interval);

startOfMonth: 2014-11-01 07:00:00 +0000
endOfMonth: 2014-12-01 07:59:58 +0000
interval: 2595600