Get the First date of previous month.

firstDateForLastMonth

-(NSDate *)firstDateForLastMonth {
    NSCalendar *cal = [NSCalendar currentCalendar];
    NSDate *now = [NSDate date];
    NSDateComponents *comp = [cal components:NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:now];
    comp.timeZone=[NSTimeZone defaultTimeZone];
    comp.month = comp.month-1;
    comp.year = comp.year;
    comp.day = 1;
    [comp setHour:0];
    [comp setMinute:0];
    [comp setSecond:0];
    NSDate *lastMonthFirstDate = [cal dateFromComponents:comp];
    return lastMonthFirstDate;
}