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;