NSDate扩展

扩展添加了获取年，月，日，时，分，秒
获取日期和时间的字符串，
获取带有偏移量的日期，前几天，前几月等
获取当前时间是在昨天还是前天等等

//
//  NSDate+Helpers.m
//  RProject
//
//  Created by ray on 2017/8/19.
//  Copyright © 2017年 ray. All rights reserved.
//

#import "NSDate+RHelpers.h"

@implementation NSDate (RHelpers)


/**
 获取当前年月日：19700101
 
 @return 19700101
 */
-(NSString *)getFormatYMD{
    return [NSString stringWithFormat:@"%lu%02lu%02lu", (unsigned long)[self getYear],(unsigned long)[self getMonth],(unsigned long)[self getDay]];
}

#pragma mark 获取日期 时间 👇


/**
 获取日
 
 @return 19
 */
-(NSUInteger)getDay{
    return [[self getDateComponents:NSCalendarUnitDay fromDate:self] day];
}

/**
 获取月
 
 @return 12
 */
-(NSUInteger)getMonth{
    return [[self getDateComponents:NSCalendarUnitMonth fromDate:self] month];
}

/**
 获取年
 
 @return 2017
 */
-(NSUInteger)getYear{
    return [[self getDateComponents:NSCalendarUnitYear fromDate:self] year];
}

/**
 获取 时
 
 @return int 几点
 */
-(int)getHour{
    return [self getHour:self];
}

/**
 获取 分
 
 @return int 几分
 */
-(int)getMinute{
    return [self getMinute:self];
}

/**
 获取 时
 
 @return int 几点
 */
-(int)getHour:(NSDate *)date{
    return (int)[[self getDateComponents:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute fromDate:date] hour];
}

/**
 获取 分
 
 @return int 几分
 */
-(int)getMinute:(NSDate *)date{
    return (int)[[self getDateComponents:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute fromDate:date] minute];
}

/**
 获取NSDateComponents对象

 @param unitFlags NSDateComponents的枚举类型 年／月／日？
 @return NSDateComponents对象
 */
-(NSDateComponents *)getDateComponents:(NSCalendarUnit)unitFlags fromDate:(NSDate *)date{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comp = [calendar components:unitFlags fromDate:date];
    return comp;
}


#pragma mark 获取时间字符串👇


/**
 获取时间字符串
 
 @param date NSDate对象
 @param format 时间格式
 @return 返回时间字符串
 */
-(NSString *)stringFromDate:(NSDate *)date withFormat:(NSString *)format{
    return [date dateStringWithFormat:format];
}

/**
 获取时间字符串
 
 @param date NSDate对象
 @return 返回时间字符串
 */
-(NSString *)stringFromDate:(NSDate *)date{
    return [date string];
}


/**
 获取时间字符串
 @param format 时间戳格式1991-01-01 12:12:12
 @return 返回时间的字符串
 */
-(NSString *)dateStringWithFormat:(NSString *)format{
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc]init];
    [outputFormatter setDateFormat:format];
    NSString *timestamp_str = [outputFormatter stringFromDate:self];
    return timestamp_str;
}


/**
 获取时间字符串
 
 @return 1970-09-01 12:12:12
 */
-(NSString *)string{
    return [self dateStringWithFormat:[NSDate datetampFormatString]];
}

/**
 获取时间字符串
 
 @param dateStyle 日期格式
 @param timeStyle 时间格式
 @return 时间字符串
 */
-(NSString *)stringWithDateStyle:(NSDateFormatterStyle)dateStyle timeStyle:(NSDateFormatterStyle)timeStyle{
    NSDateFormatter *outputFormatter = [[NSDateFormatter alloc]init];
    [outputFormatter setDateStyle:dateStyle];
    [outputFormatter setTimeStyle:timeStyle];
    NSString *outputString = [outputFormatter stringFromDate:self];
    return outputString;
}



#pragma mark NSDate offset 获取带有偏移量的日期👇


/**
 获取今天+偏移量 的日期
 
 @param day 偏移几天
 @return 偏移后的日期
 */
-(NSDate *)dateAfterDay:(int)day{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateCompToAdd = [[NSDateComponents alloc]init];
    [dateCompToAdd setDay:day];
    NSDate *dateAfterDay = [calendar dateByAddingComponents:dateCompToAdd toDate:self options:0];
    return dateAfterDay;
}


/**
 获取今天+偏移量 的日期
 
 @param month 偏移几月
 @return 偏移后的日期
 */
-(NSDate *)dateAfterMonth:(int)month{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateCompToAdd = [[NSDateComponents alloc]init];
    [dateCompToAdd setMonth:month];
    NSDate *dateAfterDay = [calendar dateByAddingComponents:dateCompToAdd toDate:self options:0];
    return dateAfterDay;
}

/**
 获取当前日期距离今天已经过去了几天
 
 @return 过去了几天
 */
-(NSUInteger)daysAgo{
    
    NSCalendar *calender = [NSCalendar currentCalendar];
    NSDateComponents *comp = [calender components:NSCalendarUnitDay fromDate:self toDate:[NSDate date] options:0];
    return [comp day];
    
}


/**
 获取日期距离今天午夜过去几天
 
 @return 过去几天
 */
-(NSUInteger)daysAgoAgainstMidnight{
    NSDateFormatter *mdf = [[NSDateFormatter alloc]init];
    [mdf setDateFormat:@"yyyy-MM-dd"];
    NSDate *midnight = [mdf dateFromString:[mdf stringFromDate:self]];
    return (int)[midnight timeIntervalSinceNow] / (60*60*24) *-1;
}


/**
 获取日期距离今天过去几天
 
 @param flag 是否是午夜之后
 @return 过去几天之后的字符串
 */
-(NSString *)stringDaysAgoAgainstMidnight:(BOOL)flag{
    
    NSUInteger daysAgo = (flag) ? [self daysAgoAgainstMidnight] : [self daysAgo];
    NSString *text = nil;
    switch (daysAgo) {
        case 0:
            text = @"今天";
            break;
        case 1:
            text = @"昨天";
            break;
        case 2:
            text = @"前天";
            break;
        default:
            text = [NSString stringWithFormat:@"%lu天前",(unsigned long)daysAgo];
            break;
    }
    return text;
}

/**
 获取日期距离今天过去几天
 
 @return 过去几天之后的字符串
 */
-(NSString *)stringDaysAgo{
    return [self stringDaysAgoAgainstMidnight:YES];
}

/**
 获取当前日期是这周的第几天
 
 @return 返回第几天
 */
-(NSUInteger)weekday{
    NSCalendar *calender = [NSCalendar currentCalendar];
    NSDateComponents *comp = [calender components:NSCalendarUnitWeekday fromDate:self];
    return [comp weekday];
}


/**
 返回当前天的年月日
 
 @return 返回日期
 */
-(NSDate *)beginningOfDay{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comp = [calendar components:(NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay) fromDate:self];
    return [calendar dateFromComponents:comp];
}

/**
 返回当前日期的所在月份的第一天日期
 
 @return 该月第一天
 */
-(NSDate *)beginningOfMonth{
    return [self dateAfterDay:-(int)[self getDay] + (int)1];
}

/**
 获取当月最后一天
 
 @return NSDate month
 */
-(NSDate *)endOfMonth{
    
    return [[[self beginningOfMonth] dateAfterMonth:1] dateAfterDay:-1];
}


/**
 返回当前周的周末日期
 
 @return NSDate 当周周末 日期
 */
-(NSDate *)endOfWeek{
    
    NSCalendar *calendar = [NSCalendar currentCalendar];
    //      获取当前日期是周几
    NSDateComponents *weekdayComp = [calendar components:NSCalendarUnitWeekday fromDate:self];
    NSDateComponents *compToAdd = [[NSDateComponents alloc]init];
    //      获取当周的周末 7-当前星期
    [compToAdd setDay:(7 - [weekdayComp weekday])];
    NSDate *endOfWeek = [calendar dateByAddingComponents:compToAdd toDate:self options:0];
    compToAdd = nil;
    return endOfWeek;
}


/**
 获取当前日期是该年的第几周
 
 @return int 几周
 */
-(int)getWeekOfYear{
    int i;
    int year = (int)[self getYear];
    NSDate *date = [self endOfWeek];
    for (i = 1; [[date dateAfterDay:-7*i] getYear] == year; i++) {
        
    }
    return i;
}

#pragma mark 获取时间戳格式字符串 👇
/**
 获取日月年格式字符串
 
 @return yyyy-MM-dd
 */
+(NSString *)dateFormatString{
    return @"yyyy-MM-dd";
}

/**
 获取时分秒格式字符串
 
 @return HH:mm:ss
 */
+(NSString *)timeFormatString{
    return @"HH:mm:ss";
}


/**
 获取时间戳格式字符串
 
 @return yyyy-MM-dd HH:mm:ss
 */
+(NSString *)timestampFormatString{
    return @"yyyy-MM-dd HH:mm:ss";
}

/**
 获取时间戳格式字符串
 
 @return yyyy-MM-dd HH:mm:ss
 */
+(NSString *)datetampFormatString{
    return [NSDate timestampFormatString];
}

#pragma mark 将时间字符串转位NSDate👇


/**
 时间字符串转位NSDate
 
 @param string 时间字符串
 @return NSDate
 */
+(NSDate *)dateFromString:(NSString *)string{
    return [NSDate dateFromString:string withFormat:[NSDate datetampFormatString]];
}

/**
 时间字符串转为NSDate
 
 @param string 时间字符串
 @param format 日期格式
 @return NSDate
 */
+(NSDate *)dateFromString:(NSString *)string withFormat:(NSString *)format{
    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    [formatter setDateFormat:format];
    return [formatter dateFromString:string];
}

#pragma mark 时间转换 将指定的时间转换为当前上／下午00:00|星期X|08-10|1999-09-01👇

/**
 获取从某日期到当前日期的显示字符串
 
 @param date NSDate对象
 @param prefixed ？
 @return 返回显示字符串
 */
+(NSString *)stringForDisplayFromDate:(NSString *)date prefixed:(BOOL)prefixed{
    
    NSDate *today = [[NSDate alloc]init];
    NSDate *dateTmp = [NSDate dateFromString:date];
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *offsetComponents = [calendar components:(NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay) fromDate:today];
    NSDate *midnight = [calendar dateFromComponents:offsetComponents];
    NSDateFormatter *displayFormatter = [[NSDateFormatter alloc]init];
    NSString *displayString = nil;
    
    if ([dateTmp compare:midnight] == NSOrderedDescending) {
        if (prefixed) {
            [displayFormatter setDateFormat:@"'at'ah:mm"];
        }else{
            [displayFormatter setDateFormat:@"ah:mm"];
        }
    }else{
        //        判断是否是最近七天
        NSDateComponents *compToSubstract = [[NSDateComponents alloc]init];
        [compToSubstract setDay:-7];
        NSDate *lastWeek = [calendar dateByAddingComponents:compToSubstract toDate:today options:0];
        if ([dateTmp compare:lastWeek] == NSOrderedDescending) {
            [displayFormatter setDateFormat:@"EEEE"];
        } else {
            //            判断年分
            NSInteger thisYear = [offsetComponents year];
            NSDateComponents *dateComp = [calendar components:(NSCalendarUnitYear|NSCalendarUnitMonth) fromDate:dateTmp];
            NSInteger thatYear = [dateComp year];
            if (thatYear >= thisYear) {
                [displayFormatter setDateFormat:@"MM-dd"];
            } else {
                [displayFormatter setDateFormat:@"yyyy-MM-dd"];
            }
        }
        if (prefixed) {
            NSString *dateFormat = [displayFormatter dateFormat];
            NSString *prefix = @"on";
            [displayFormatter setDateFormat:[prefix stringByAppendingString:dateFormat]];
        }
    }
    displayString = [displayFormatter stringFromDate:dateTmp];
    return displayString;
}


/**
 获取从某日期到当前日期的显示字符串
 
 @param date NSDate对象
 @return 返回时间字符串
 */
+(NSString *)stringForDisplayFromDate:(NSString *)date{
    return [NSDate stringForDisplayFromDate:date prefixed:NO];
}
@end