IOS 十位数0补齐

NSCalendar *calendar = [NSCalendar currentCalendar];

        unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit;

        NSDateComponents *components = [calendar components:unitFlags fromDate:[NSDate date]];

        NSInteger iCurYear = [components year];  //当前的年份

        NSInteger iCurMonth = [components month];  //当前的月份

        NSString *iStr = [NSString stringWithFormat:@"%02d",iCurMonth];

        NSInteger iCurDay = [components day];  // 当前的号数

        calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

        NSRange range = [calendar rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:[NSDate date]];

        NSUInteger numberOfDaysInMonth = range.length;