IOS自定义日历控件的简单实现(附思想及过程)

Posted 2020-08-11

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因为程序要求要插入一个日历控件,该空间的要求是从当天开始及以后的六个月内的日历,上网查资料基本上都说只要获取两个条件(当月第一天周几和本月一共有多少天)就可以实现一个简单的日历,剩下的靠自己的简单逻辑就OK了,下面开始自己从开始到完成的整个过程

1,首先做NSDate类目,扩展一些方法让日期之间转换更加方便

#import <Foundation/Foundation.h>

@interface NSDate (LYWCalendar)

#pragma mark - 获取日
- (NSInteger)day:(NSDate *)date;
#pragma mark - 获取月
- (NSInteger)month:(NSDate *)date;
#pragma mark - 获取年
- (NSInteger)year:(NSDate *)date;
#pragma mark - 获取当月第一天周几
- (NSInteger)firstWeekdayInThisMonth:(NSDate *)date;
#pragma mark - 获取当前月有多少天
- (NSInteger)totaldaysInMonth:(NSDate *)date;

@end

下面一一实现这些方法

#import "NSDate+LYWCalendar.h"

@implementation NSDate (LYWCalendar)

/**
 *实现部分
 */
#pragma mark -- 获取日
- (NSInteger)day:(NSDate *)date{
    NSDateComponents *components = [[NSCalendar currentCalendar] components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
    return components.day;
}

#pragma mark -- 获取月
- (NSInteger)month:(NSDate *)date{
    NSDateComponents *components = [[NSCalendar currentCalendar] components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
    return components.month;
}

#pragma mark -- 获取年
- (NSInteger)year:(NSDate *)date{
    NSDateComponents *components = [[NSCalendar currentCalendar] components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
    return components.year;
}

#pragma mark -- 获得当前月份第一天星期几
- (NSInteger)firstWeekdayInThisMonth:(NSDate *)date{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    //设置每周的第一天从周几开始,默认为1,从周日开始
    [calendar setFirstWeekday:1];//1.Sun. 2.Mon. 3.Thes. 4.Wed. 5.Thur. 6.Fri. 7.Sat.
    NSDateComponents *comp = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:date];
    [comp setDay:1];
    NSDate *firstDayOfMonthDate = [calendar dateFromComponents:comp];
    NSUInteger firstWeekday = [calendar ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitWeekOfMonth forDate:firstDayOfMonthDate];
    //若设置从周日开始算起则需要减一,若从周一开始算起则不需要减
    return firstWeekday - 1;
}
#pragma mark -- 获取当前月共有多少天

- (NSInteger)totaldaysInMonth:(NSDate *)date{
    NSRange daysInLastMonth = [[NSCalendar currentCalendar] rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:date];
    return daysInLastMonth.length;
}

接下来就要写逻辑部分了,在ViewController里面实现,先说思想,首先想到的是用collectionView,但是每个月天数不一样在日历中的显示就不一样,有时候有五行有时候有六行,既然要用自动填充就必须考虑到这一点,下面是代码实现

#import "ViewController.h"
#import "Macro.h"
#import "NSDate+LYWCalendar.h"
#import "LYWCollectionViewCell.h"
#import "LYWCollectionReusableView.h"

定义一些全局变量

static NSString *cellID = @"cellID";
static NSString *headerID = @"headerID";
static NSString *footerID = @"footerID";

@implementation ViewController
{
    //自动布局
    UICollectionViewFlowLayout *_layout;
    //表格视图
    UICollectionView *_collectionView;
    //当月第一天星期几
    NSInteger firstDayInMounthInWeekly;
    NSMutableArray *_firstMounth;
    //容纳六个数组的数组
    NSMutableArray *_sixArray;
    
}

//定义星期视图,若为周末则字体颜色为绿色
    self.automaticallyAdjustsScrollViewInsets = NO;//关闭自动适应
    NSArray *weekTitleArray = @[@"周日",@"周一",@"周二",@"周三",@"周四",@"周五",@"周六"];
    for (int i = 0; i < weekTitleArray.count; i++) {
        UILabel *weekTitleLable = [[UILabel alloc]initWithFrame:CGRectMake(i * ((ScreenWidth/(weekTitleArray.count))), 64, ScreenWidth/(weekTitleArray.count ), 30)];
        if (i == 0 || i == 6) {
            weekTitleLable.textColor = [UIColor greenColor];
        }else{
            weekTitleLable.textColor = [UIColor blackColor];
        }
        weekTitleLable.text = [weekTitleArray objectAtIndex:i];
        weekTitleLable.textAlignment = NSTextAlignmentCenter;
        [self.view addSubview:weekTitleLable];
}

//设置collectionView及自动布局,代理方法尤为重要
    _layout = [[UICollectionViewFlowLayout alloc]init];
    //头部始终在顶端
    _layout.sectionHeadersPinToVisibleBounds = YES;
    //头部视图高度
    _layout.headerReferenceSize = CGSizeMake(414, 40);
    _layout.minimumLineSpacing = 0;
    _layout.minimumInteritemSpacing = 0;
    _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 64 + 30, ScreenWidth, ScreenHeight - 64 - 30) collectionViewLayout:_layout];
    _collectionView.backgroundColor = [UIColor whiteColor];
    //注册表格
    [_collectionView registerClass:[LYWCollectionViewCell class] forCellWithReuseIdentifier:cellID];
    //注册头视图
    [_collectionView registerClass:[LYWCollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:headerID];
    //注册尾视图
//    [_collectionView registerClass:[UICollectionReusableView class] forCellWithReuseIdentifier:footerID];
　　 _collectionView.delegate = self;
    _collectionView.dataSource = self;
    [self.view addSubview:_collectionView];

逻辑部分,这里有个比较长的三项表达式

(daysInMounth > 29 && (firstDayInThisMounth == 6 || firstDayInThisMounth ==5) ? 42 : 35)

就是日历到底是六行还是七行,这就要根据日历的特性来判断了,如果当月天数大于29天并且当月第一天星期六(以这个程序的准则)或者星期天是返回六行剩下的返回三行,也有可能返回四行的,但是就这个程序来说是不可能的也就不需要做判断了

 //NumberMounthes 为宏定义,表示要显示月的个数,程序要求是六个月,所以宏定义为六

　　//#define NumberMounthes 6 //想要展示的月数

//创建六个数组,并将这六个数组装入大数组中
    _sixArray = [[NSMutableArray alloc]init];
    for (int i = 0; i < NumberMounthes ; i++ ) {
        NSMutableArray *array = [[NSMutableArray alloc]init];
        [_sixArray addObject:array];
    }
    //为六个数组写入每个月的日历信息
    for (int i = 0 ; i < NumberMounthes; i++) {
        //获取月份
        int mounth = ((int)[currentDate month:currentDate] + i)%12;
        NSDateComponents *components = [[NSDateComponents alloc]init];
        //获取下个月的年月日信息,并将其转为date
        components.month = mounth;
        components.year = 2016 + mounth/12;
        components.day = 1;
        NSCalendar *calendar = [NSCalendar currentCalendar];
        NSDate *nextDate = [calendar dateFromComponents:components];
        //获取该月第一天星期几
        NSInteger firstDayInThisMounth = [nextDate firstWeekdayInThisMonth:nextDate];
        //该月的有多少天daysInThisMounth
        NSInteger daysInThisMounth = [nextDate totaldaysInMonth:nextDate];
        NSString *string = [[NSString alloc]init];
        for (int j = 0; j < (daysInMounth > 29 && (firstDayInThisMounth == 6 || firstDayInThisMounth ==5) ? 42 : 35) ; j++) {
            if (j < firstDayInThisMounth || j > daysInThisMounth + firstDayInThisMounth - 1) {
                string = @"";
                [[_sixArray objectAtIndex:i]addObject:string];
            }else{
                string = [NSString stringWithFormat:@"%ld",j - firstDayInThisMounth + 1];
                [[_sixArray objectAtIndex:i]addObject:string];
            }
        }
    }

下面是代理方法

//这两个不用说,返回cell个数及section个数
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
    return [[_sixArray objectAtIndex:section] count];
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{
    return _sixArray.count;
}

//这里是自定义cell,非常简单的自定义
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    LYWCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellID  forIndexPath:indexPath];
    UIView *blackgroundView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, cell.frame.size.width, cell.frame.size.height)];
    blackgroundView.backgroundColor = [UIColor yellowColor];
    cell.dateLable.text = [[_sixArray objectAtIndex:indexPath.section]objectAtIndex:indexPath.row];
    NSDate *date = [[NSDate alloc]init];
    NSInteger day = [date day:date];
　　//设置单击后的颜色
  　　cell.selectedBackgroundView = blackgroundView;
    return cell;
}

自定义cell .h

#import <UIKit/UIKit.h>

@interface LYWCollectionViewCell : UICollectionViewCell

@property (nonatomic,strong) UILabel *dateLable;

- (instancetype)initWithFrame:(CGRect)frame;

@end

#import "LYWCollectionViewCell.h"

@implementation LYWCollectionViewCell

- (instancetype)initWithFrame:(CGRect)frame{
    if (self == [super initWithFrame:frame]) {
       _dateLable = [[UILabel alloc] initWithFrame:self.bounds];
        [_dateLable setTextAlignment:NSTextAlignmentCenter];
        [_dateLable setFont:[UIFont systemFontOfSize:17]];
        _dateLable.textColor = [UIColor blackColor];
        [self addSubview:_dateLable];
    }
    return self;
}

@end

接着代理

//cell大小及间距
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{
    return CGSizeMake(ScreenWidth/7, ScreenWidth/7);
}

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{
    return UIEdgeInsetsMake(0, 0, 0, 0);
}

既然有日历,总得显示哪年哪月吧,前面已经注册表头视图了,这里只需要实现以下代理方法即可

collectionView有点不同其头视图也有单独的类,和cell一样先自定义headCell,也是非常简单的自定义

.h文件

#import <UIKit/UIKit.h>

@interface LYWCollectionReusableView : UICollectionReusableView

@property (nonatomic,strong) UILabel *dateLable;

- (instancetype)initWithFrame:(CGRect)frame;

@end

.m文件

#import "LYWCollectionReusableView.h"

@implementation LYWCollectionReusableView

- (instancetype)initWithFrame:(CGRect)frame{
    if (self == [super initWithFrame:frame]) {
        _dateLable = [[UILabel alloc] initWithFrame:self.bounds];
        [_dateLable setTextAlignment:NSTextAlignmentLeft];
        [_dateLable setFont:[UIFont systemFontOfSize:20]];
        _dateLable.textColor = [UIColor blackColor];
        [self addSubview:_dateLable];
    }
    return self;
}

@end

接着代理方法,这里也有个三项判断式,和上面的大同小异,主要是防止12月显示为0月

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{
    if (kind == UICollectionElementKindSectionHeader) {
        LYWCollectionReusableView *headerRV = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:headerID forIndexPath:indexPath];
        //自定义蓝色
        headerRV.backgroundColor = DODGER_BLUE;
        NSDate *currentDate = [[NSDate alloc]init];
        NSInteger year = ([currentDate month:currentDate] + indexPath.section)/12 + 2016;
        NSInteger mounth = ([currentDate month:currentDate] + indexPath.section) % 12 == 0 ? 12 : ([currentDate month:currentDate] + indexPath.section)%12;
        headerRV.dateLable.text = [NSString stringWithFormat:@"%ld年%ld月",year,mounth];
        return headerRV;
    }else{
        return nil;
    }
}