两个时间进行比较使用NSCalendar 日历类进行对比

本文链接：https://blog.youkuaiyun.com/user_begin/article/details/49157969

本文详细阐述了如何使用Objective-C编程语言进行时间比较、日期判断及格式转换，包括判断两个时间是否在同一年、是否为昨天或今天，以及如何通过日期格式转换计算日期差。文章还提供了具体的代码实现，涵盖了日期格式的转换、日期比较和时间差计算等关键步骤。

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整体逻辑

//时间的比较需要可以使用日历得到两个时间的具体信息

NSDateComponents *comp = [lendar components:unit fromDate:date];
NSDateComponents *lastComp = [lendar components:unit fromDate:lastDate];

//判断两个时间是否在同一年获取两个时间的具体信息比较年是否一样

NSCalendar *lendar = [NSCalendar currentCalendar];
NSDateComponents *comp = [lendar components:NSCalendarUnitYear fromDate:[NSDate date]];
NSDateComponents *lastComp = [lendar components:NSCalendarUnitYear fromDate:date];
return comp.year == lastComp.year;

//判断是昨天还是今天，先讲时间格式转化成只有年月日，再将两个时间做比较，当年月都等于0，日差一天是返回的是昨天（其实这里转不转年月日的格式都可以，只要确保年月是相同的日差一天就得来）

NSDate *newDate = [NSDate date];

    //1.将格式转化成只有年月日
    NSDateFormatter *matter = [[NSDateFormatter alloc]init];
    matter.dateFormat = @"yyyy-mm-dd";
    //转换成字符串
    NSString *dateStr = [matter stringFromDate:date];
    NSString *newstr = [matter stringFromDate:newDate];

    //2.将字符串再转换成时间计算年月日就可以来
    date = [matter dateFromString:dateStr];
    newDate = [matter dateFromString:newstr];

    //3.比较两个时间的具体差
    NSCalendar *lendar = [NSCalendar currentCalendar];
    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
    NSDateComponents *comp = [lendar components:unit fromDate:date toDate:newDate options:0];

    return comp.year == 0 && comp.month == 0 && comp.day == 1;

//判断是不是今天

    NSCalendar *lendar = [NSCalendar currentCalendar];
    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
    NSDateComponents *comp = [lendar components:unit fromDate:[NSDate date] toDate:date options:0];
    return comp.year == 0 && comp.month == 0 && comp.day == 0;

具体代码实现

// * 将字符串转换成时间

    NSString *str = @"2014/12/1 12:13:34";

    NSDateFormatter *matter = [[NSDateFormatter alloc]init];

    matter.dateFormat = @"yyyy/MM/dd HH:mm:ss";

    NSDate *lastDate = [matter dateFromString:str];

    //* 现在的时间
    NSDate *date = [NSDate date];


    //1.使用日历对象（比较两个时间）创建一个日历
    NSCalendar *lendar = [NSCalendar currentCalendar];

    //2.获取想要的差值年－月－日－时－分－秒
    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond ;


    //3.得到两个具体时间的年月日时分秒
    NSDateComponents *comp = [lendar components:unit fromDate:date];
    NSDateComponents *lastComp = [lendar components:unit fromDate:lastDate];

    //4.比较两个时间的时间差
    NSDateComponents *poor = [lendar components:unit fromDate:date toDate:lastDate options:nil];

／／判断是不是同一年

- (BOOL)poorYear:(NSDate*)date{

    NSCalendar *lendar = [NSCalendar currentCalendar];
    NSDateComponents *comp = [lendar components:NSCalendarUnitYear fromDate:[NSDate date]];
    NSDateComponents *lastComp = [lendar components:NSCalendarUnitYear fromDate:date];
    return comp.year == lastComp.year;

}

／／判断是否为昨天

- (BOOL)poorDay:(NSDate*)date{
    NSDate *newDate = [NSDate date];

    //1.将格式转化成只有年月日
    NSDateFormatter *matter = [[NSDateFormatter alloc]init];
    matter.dateFormat = @"yyyy-mm-dd";
    //转换成字符串
    NSString *dateStr = [matter stringFromDate:date];
    NSString *newstr = [matter stringFromDate:newDate];

    //2.将字符串再转换成时间计算年月日就可以来
    date = [matter dateFromString:dateStr];
    newDate = [matter dateFromString:newstr];

    //3.比较两个时间的具体差
    NSCalendar *lendar = [NSCalendar currentCalendar];
    NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
    NSDateComponents *comp = [lendar components:unit fromDate:date toDate:newDate options:0];

    return comp.year == 0 && comp.month == 0 && comp.day == 1;
}