日曆（iOS）陽曆+農曆

效果如動圖：

日曆.gif

傳入年份，返回給你一年的數據：

//調用的接口
- (NSMutableArray *)getNumberOfDaysInMonthByYear:(NSString *)whichYear;

實現的具體代碼：

// 獲取一年中每月的總天數
- (NSMutableArray *)getNumberOfDaysInMonthByYear:(NSString *)whichYear
{
NSCalendar * calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian]; // 指定日曆的算法
NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy-MM-dd"];
NSMutableArray *allYaerMonthDayCountArray = [[NSMutableArray alloc] init];

for (int j=0; j<12; j++) {
    NSMutableDictionary *dicM = [[NSMutableDictionary alloc] init];
    NSString * dateStr = [NSString stringWithFormat:@"%@-%02d-01",whichYear,j+1];
    NSDate * currentDate = [formatter dateFromString:dateStr];
    NSRange range = [calendar rangeOfUnit:NSCalendarUnitDay
                                   inUnit: NSCalendarUnitMonth
                                  forDate:currentDate];
    
    [formatter setDateFormat:@"yyyy-MM"];
    NSString * str = [formatter stringFromDate:currentDate];
    [formatter setDateFormat:@"yyyy-MM-dd"];
    NSMutableArray * allDaysArray = [[NSMutableArray alloc] init];
    for (NSInteger i = 1; i <= range.length; i++) {
        NSString * sr = [NSString stringWithFormat:@"%@-%ld",str,i];
        NSDate *suDate = [formatter dateFromString:sr];
        [allDaysArray addObject:[self getweekDayWithDate:suDate]];
    }
    
    [dicM setObject:@(range.length) forKey:@"monthAllDayCount"];
    [dicM setObject:allDaysArray forKey:@"monthWeekArray"];
    [allYaerMonthDayCountArray addObject:dicM];
}

return allYaerMonthDayCountArray;
}

/**
 *  獲得某天的數據
 *
 *  獲取指定的日期是星期幾
 */
- (id) getweekDayWithDate:(NSDate *) date
{
NSCalendar * calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian]; // 指定日曆的算法
NSDateComponents *comps = [calendar components:NSCalendarUnitWeekday fromDate:date];
// 1 是週日，2是週一 3.以此類推
return @([comps weekday]);

}

返回的數據結構如下圖：

返回的數據結構.png

上面的這些都是處理陽曆數據，如果需要顯示農曆和對應的節假日什麼的，也提供了一個接口，

// 獲取date當天的農曆
-(NSString*)getChineseCalendarWithDate:(NSString*)date;

需要傳入"2017-01-01"這樣的日期字符串。具體代碼如下：

-(NSString*)getChineseCalendarWithDate:(NSString*)date{
NSArray *chineseYears = [NSArray arrayWithObjects:
                         @"甲子", @"乙丑", @"丙寅", @"丁卯",  @"戊辰",  @"己巳",  @"庚午",  @"辛未",  @"壬申",  @"癸酉",
                         @"甲戌",   @"乙亥",  @"丙子",  @"丁丑", @"戊寅",   @"己卯",  @"庚辰",  @"辛己",  @"壬午",  @"癸未",
                         @"甲申",   @"乙酉",  @"丙戌",  @"丁亥",  @"戊子",  @"己丑",  @"庚寅",  @"辛卯",  @"壬辰",  @"癸巳",
                         @"甲午",   @"乙未",  @"丙申",  @"丁酉",  @"戊戌",  @"己亥",  @"庚子",  @"辛丑",  @"壬寅",  @"癸丑",
                         @"甲辰",   @"乙巳",  @"丙午",  @"丁未",  @"戊申",  @"己酉",  @"庚戌",  @"辛亥",  @"壬子",  @"癸丑",
                         @"甲寅",   @"乙卯",  @"丙辰",  @"丁巳",  @"戊午",  @"己未",  @"庚申",  @"辛酉",  @"壬戌",  @"癸亥", nil];

NSArray *chineseMonths=[NSArray arrayWithObjects:
                        @"正月", @"二月", @"三月", @"四月", @"五月", @"六月", @"七月", @"八月",
                        @"九月", @"十月", @"十一月", @"臘月", nil];

NSArray *chineseDays=[NSArray arrayWithObjects:
                      @"初一", @"初二", @"初三", @"初四", @"初五", @"初六", @"初七", @"初八", @"初九", @"初十",
                      @"十一", @"十二", @"十三", @"十四", @"十五", @"十六", @"十七", @"十八", @"十九", @"二十",
                      @"廿一", @"廿二", @"廿三", @"廿四", @"廿五", @"廿六", @"廿七", @"廿八", @"廿九", @"三十",  nil];

NSDate *dateTemp = nil;
NSDateFormatter *dateFormater = [[NSDateFormatter alloc]init];
[dateFormater setDateFormat:@"yyyy-MM-dd"];
dateTemp = [dateFormater dateFromString:date];
NSCalendar *localeCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierChinese];
unsigned unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth |  NSCalendarUnitDay;
NSDateComponents *localeComp = [localeCalendar components:unitFlags fromDate:dateTemp];
 //   NSLog(@"%ld_%ld_%ld  %@",(long)localeComp.year,(long)localeComp.month,(long)localeComp.day, localeComp.date);
NSString *y_str = [chineseYears objectAtIndex:localeComp.year-1];
NSString *m_str = [chineseMonths objectAtIndex:localeComp.month-1];
NSString *d_str = [chineseDays objectAtIndex:localeComp.day-1];
NSString *chineseCal_str =nil;
NSString *choose_str = [NSString stringWithFormat: @"%@%@",m_str,d_str];
NSString *riqi_str = [date substringWithRange:NSMakeRange(5, 5)];
if ([d_str isEqualToString:@"初一"]) {
    chineseCal_str =[NSString stringWithFormat: @"%@",m_str];
}else{
    if ([riqi_str isEqualToString:@"01-01"]) {
        chineseCal_str = @"元旦節";
    }else if([riqi_str isEqualToString:@"04-01"]){
        chineseCal_str = @"愚人節";
    }else if([riqi_str isEqualToString:@"05-01"]){
        chineseCal_str = @"勞動節";
    }else if([riqi_str isEqualToString:@"06-01"]){
        chineseCal_str = @"兒童節";
    }else if([riqi_str isEqualToString:@"07-01"]){
        chineseCal_str = @"建軍節";
    }else if([riqi_str isEqualToString:@"08-01"]){
        chineseCal_str = @"建黨節";
    }else if([riqi_str isEqualToString:@"09-10"]){
        chineseCal_str = @"教師節";
    }else if([riqi_str isEqualToString:@"10-01"]){
        chineseCal_str = @"國慶節";
    }else if([riqi_str isEqualToString:@"12-25"]){
        chineseCal_str = @"聖誕節";
    }else if ([choose_str isEqualToString:@"臘月三十"]) {
        chineseCal_str = @"除夕夜";
    }else if ([choose_str isEqualToString:@"正月十五"]){
        chineseCal_str =@"元宵節";
    }else if ([choose_str isEqualToString:@"二月初二"]){
        chineseCal_str =@"龍頭節";
    }else if ([choose_str isEqualToString:@"三月初八"]){
        chineseCal_str =@"清明節";
    }else if ([choose_str isEqualToString:@"五月初五"]){
        chineseCal_str =@"端午節";
    }else if ([choose_str isEqualToString:@"八月十五"]){
        chineseCal_str =@"中秋節";
    }else{
        chineseCal_str =[NSString stringWithFormat: @"%@",d_str];
    }
}
return chineseCal_str;
}

數據準備就這些，下面就是如何處理並顯示的問題了。
這個demo採用的是collectioncell顯示的，數據中兩個比較關鍵的值一個是當月共多少天，一個是當月第一天是周幾。因爲collectioncell在顯示的時候從左至右一排一排排列的，但是不可能每月的一號都在第一個位置，我做的處理是，根據當月第一天是周幾，collectioncell從第幾個indexpath.row+1-周幾 的那個位置開始顯示，cell的數量順序增加周幾個數。

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
LFCalendarCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"LFCalendarCollectionViewCell" forIndexPath:indexPath];
LFCanlendarModel *model = self.sourceDataArray[indexPath.section];
NSArray *arr = model.monthWeekArray;
NSInteger number = indexPath.row+1-[arr[0] integerValue];
if (number>=0) {
    [cell setCellStylebyIndexPath:indexPath withNowInteger:number+1 withYear:yearStr];
}else{
    [cell setCellStylebyIndexPath:indexPath withNowInteger:0  withYear:yearStr];
}
return cell;
}

需要代碼的可以去https://github.com/marsLiuFei/CalendarDemo 進行下載。代碼不是很嚴謹，但總體效果能實現。如果有好的修改方案，還希望在GitHub給予fork修改。共同學習，謝謝！