字符串时间转成，昨天，今天，明天格式

//获取 字符串

1.

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

    [outputFormatter setLocale:[NSLocale currentLocale]];

    [outputFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

    NSDate *strDate = [outputFormatter dateFromString:image.beginTime];

    //修正8小时的差时

    NSTimeZone *zone = [NSTimeZone systemTimeZone];

    NSInteger interval = [zone secondsFromGMTForDate: strDate];

    NSDate *endDate = [strDate  dateByAddingTimeInterval: interval];

    NSString *lastTime = [self compareDate:endDate];

//给字符串所在的控件赋值，一般在setmodel中赋值显示

   self.timelabel.text = [NSString stringWithFormat:@"%@开播",lastTime];

//调用方法compareDate方法

-(NSString *)compareDate:(NSDate *)date{

    

    NSTimeInterval secondsPerDay = 24 * 60 * 60;

    

    //修正8小时之差

    NSDate *date1 = [NSDate date];

    NSTimeZone *zone = [NSTimeZone systemTimeZone];

    NSInteger interval = [zone secondsFromGMTForDate: date1];

    NSDate *localeDate = [date1  dateByAddingTimeInterval: interval];

    

    //NSLog(@"nowdate=%@ olddate = %@",localeDate,date);

    NSDate *today = localeDate;

    NSDate *yesterday,*beforeOfYesterday;

    //今年

    NSString *toYears;

    

    toYears = [[today description] substringToIndex:4];

    

    yesterday = [today dateByAddingTimeInterval: secondsPerDay];

    beforeOfYesterday = [yesterday dateByAddingTimeInterval: secondsPerDay];

    

    NSString *todayString = [[today description] substringToIndex:10];

    NSString *yesterdayString = [[yesterday description] substringToIndex:10];

    NSString *beforeOfYesterdayString = [[beforeOfYesterday description] substringToIndex:10];

    

    NSString *dateString = [[date description] substringToIndex:10];

    NSString *dateYears = [[date description] substringToIndex:4];

    

    NSString *dateContent;

    if ([dateYears isEqualToString:toYears]) {//同一年

        //今 昨 前天的时间

        NSString *time = [[date description] substringWithRange:(NSRange){11,5}];

        //其他时间

        NSString *time2 = [[date description] substringWithRange:(NSRange){5,11}];

        if ([dateString isEqualToString:todayString]){

            dateContent = [NSString stringWithFormat:@"今天 %@",time];

            return dateContent;

        } else if ([dateString isEqualToString:yesterdayString]){

            dateContent = [NSString stringWithFormat:@"明天 %@",time];

            return dateContent;

        }else if ([dateString isEqualToString:beforeOfYesterdayString]){

            dateContent = [NSString stringWithFormat:@"前天 %@",time];

            return dateContent;

        }else{

            return time2;

        }

    }else{

        return dateString;

    }

}