Object-C学习之NSDate

//获得2004年5月6日是星期几， 实际是周二 
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:11];
[comps setMonth:12];
[comps setYear:2012];
NSCalendar *gregorian = [[NSCalendar alloc]
    initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [gregorian dateFromComponents:comps];
[comps release];
NSDateComponents *weekdayComponents =
    [gregorian components:NSWeekdayCalendarUnit fromDate:date];
int weekday = [weekdayComponents weekday];
NSLog(@"%d",weekday);   //周二，值为3

 

 

 

//每一秒更新倒计时
- (void)timerFireMethod:(NSTimer*)theTimer
{
    NSDateFormatter *dateformatter = [[[NSDateFormatter alloc]init] autorelease];//定义NSDateFormatter用来显示格式
    [dateformatter setDateFormat:@"yyyy MM dd hh mm ss"];//设定格式
    NSCalendar *cal = [NSCalendarcurrentCalendar];//定义一个NSCalendar对象
    NSDate *todate = [cal dateFromComponents:startTime];
    NSDate *today = [NSDate date];
    unsignedint unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

    t = [cal components:unitFlags fromDate:today toDate:todate options:0];
    clockDown.text = [NSStringstringWithFormat:@"剩余:%02d:%02d",[t minute], [t second]];

    //若超时
    if([t minute] <= 0 && [t second] <= 0)
    {
        [downClock invalidate];
        UIAlertView *timeover = [[UIAlertViewalloc] initWithTitle:nilmessage:@"考试时间已到" delegate:selfcancelButtonTitle:@"交卷"otherButtonTitles:nil, nil];
        timeover.tag = 1002;
        [timeover show];
        [timeover release];
        clockDown.text = [NSString stringWithFormat:@"剩余:%02d:%02d",0, 0];
    }

}

 

 

 

 

 

 

 

 

 

以下部分转自angellixf的博客： Objective-c NSDate 取时间，日期，星期，毫秒等，感觉很不错，没改动直接上代码了

 

//得到当前的日期
    //    NSDate *date = [NSDate date];
    //    NSLog(@"date:%@",date);

    //得到(24 * 60 * 60)即24小时之前的日期，dateWithTimeIntervalSinceNow:
    NSDate *yesterday = [NSDate dateWithTimeIntervalSinceNow: -(24 * 60 * 60)];
    NSLog(@"yesterday:%@",yesterday);

    NSDateFormatter *formatter =[[[NSDateFormatteralloc] init] autorelease];
    NSDate *date = [NSDate date];
    [formatter setTimeStyle:NSDateFormatterMediumStyle];
    NSCalendar *calendar = [[[NSCalendaralloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
    NSDateComponents *comps = [[[NSDateComponentsalloc] init] autorelease];
    NSInteger unitFlags = NSYearCalendarUnit | 
    NSMonthCalendarUnit |
    NSDayCalendarUnit | 
    NSWeekdayCalendarUnit | 
    NSHourCalendarUnit |
    NSMinuteCalendarUnit |
    NSSecondCalendarUnit;
    //int week=0;
    comps = [calendar components:unitFlags fromDate:date];
    int week = [comps weekday]; 
    int year=[comps year]; 
    int month = [comps month];
    int day = [comps day];
    //[formatter setDateStyle:NSDateFormatterMediumStyle];
    //This sets the label with the updated time.
    int hour = [comps hour];
    int min = [comps minute];
    int sec = [comps second];
    NSLog(@"week%d",week);
    NSLog(@"year%d",year);
    NSLog(@"month%d",month);
    NSLog(@"day%d",day);
    NSLog(@"hour%d",hour);
    NSLog(@"min%d",min);
    NSLog(@"sec%d",sec);


    //得到毫秒
    NSDateFormatter *dateFormatter = [[NSDateFormatteralloc] init];
    [dateFormatter setDateStyle:NSDateFormatterMediumStyle];
    [dateFormatter setTimeStyle:NSDateFormatterShortStyle];
    //[dateFormatter setDateFormat:@"hh:mm:ss"]
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss.SSS"];
    NSLog(@"Date%@", [dateFormatter stringFromDate:[NSDate date]]);
    [dateFormatter release];