iOS开发·NSDate日期基本操作方法

    NSDate *myDate = [NSDate date];
    NSLog(@"myDate = %@",myDate);

    NSTimeInterval secondsPerDay = 24*60*60;
    NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:secondsPerDay];
    NSLog(@"myDate = %@",tomorrow);

    NSTimeInterval secondsPerDay1 = 24*60*60;
    NSDate *now = [NSDate date];
    NSDate *yesterDay = [now addTimeInterval:-secondsPerDay1];
    NSLog(@"yesterDay = %@",yesterDay);

    BOOL sameDate = [now isEqualToDate:yesterDay];
    NSLog(@"sameDate = %lu",sameDate);

    NSDate *earlierDate = [yesterDay earlierDate:now];
    NSLog(@"earlierDate  = %@",earlierDate);

    NSDate *laterDate = [yesterDay laterDate:now];
    NSLog(@"laterDate  = %@",laterDate);

    NSTimeInterval secondsBetweenDates= [yesterDay timeIntervalSinceDate:now];
    NSLog(@"secondsBetweenDates=  %lf",secondsBetweenDates);

    NSDateComponents *comp = [[NSDateComponentsalloc]init]; 
    [comp setMonth:06]; 
    [comp setDay:01];
    [comp setYear:2001];
    NSCalendar *myCal = [[NSCalendaralloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDate *myDate1 = [myCal dateFromComponents:comp];
    NSLog(@"myDate1 = %@",myDate1);

    unsigned units  = NSMonthCalendarUnit|NSDayCalendarUnit|NSYearCalendarUnit; 
    NSDateComponents *comp1 = [myCal components:units fromDate:now]; 
    NSInteger month = [comp1 month]; 
    NSInteger year = [comp1 year]; 
    NSInteger day = [comp1 day]; 

    NSDateFormatter *formatter = [[NSDateFormatteralloc]init]; 
    [formatter setDateStyle:NSDateFormatterFullStyle];//直接输出的话是机器码 
    //或者是手动设置样式[formatter setDateFormat:@"yyyy-mm-dd"]; 
    NSString *string = [formatter stringFromDate:now]; 
    NSLog(@"string = %@",string); 
    NSLog(@"formater = %@",formatter); 

- (NSDateFormatter *)dateFormatter {
    if (dateFormatter == nil) {
        dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateStyle:NSDateFormatterMediumStyle];
        [dateFormatter setTimeStyle:NSDateFormatterNoStyle];
    }
    return dateFormatter;
}

//获取被比较的指定日期
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];  
[dateFormatter setDateFormat:@"dd-MM-yyyy-HHmmss"];  
NSDate *date = [dateFormatter dateFromString:@"30-09-2016-000000"];
//调用
[self compareOneDay:[self getCurrentTime] withAnotherDay:date]  

#pragma mark -得到当前时间  
- (NSDate *)getCurrentTime{  
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];  
    [formatter setDateFormat:@"dd-MM-yyyy-HHmmss"];  
    NSString *dateTime=[formatter stringFromDate:[NSDate date]];  
    NSDate *date = [formatter dateFromString:dateTime];  
      
    NSLog(@"---------- currentDate == %@",date);  
    return date;  
}  

- (int)compareOneDay:(NSDate *)oneDay withAnotherDay:(NSDate *)anotherDay  
{  
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];  
    [dateFormatter setDateFormat:@"dd-MM-yyyy-HHmmss"];  
    NSString *oneDayStr = [dateFormatter stringFromDate:oneDay];  
    NSString *anotherDayStr = [dateFormatter stringFromDate:anotherDay];  
    NSDate *dateA = [dateFormatter dateFromString:oneDayStr];  
    NSDate *dateB = [dateFormatter dateFromString:anotherDayStr];  
    NSComparisonResult result = [dateA compare:dateB];  
    NSLog(@"date1 : %@, date2 : %@", oneDay, anotherDay);  
    if (result == NSOrderedDescending) {  
        //NSLog(@"Date1  is in the future");  
        return 1;  
    }  
    else if (result == NSOrderedAscending){  
        //NSLog(@"Date1 is in the past");  
        return -1;  
    }  
    //NSLog(@"Both dates are the same");  
    return 0;  
}