Objective-c_Date 日期对象

 NSDate *date = [NSDate date];

        NSLog(@"%@",date);

        NSLog(@"%@",[date descriptionWithLocale:[NSLocale currentLocale]]);

        

        NSDate *date1 = [NSDate dateWithTimeIntervalSince1970:60*60*12];

        NSLog(@"%@",[date1 descriptionWithLocale:[NSLocale currentLocale]]);

        

        NSDate *date2 = [NSDate distantFuture];

        NSLog(@"%@",date2);

         NSLog(@"%@",[date2 descriptionWithLocale:[NSLocale currentLocale]]);

        

        NSDate *date3 = [NSDate distantPast];

      NSLog(@"%@",[date3 descriptionWithLocale:[NSLocale currentLocale]]);

        

        //NSDate的比较

        NSDate *later= [date3 laterDate:date2];

         NSLog(@"%@",[later descriptionWithLocale:[NSLocale currentLocale]]);

        

        NSDate *earlier = [date3 earlierDate:date2];

        NSLog(@"%@",[earlier descriptionWithLocale:[NSLocale currentLocale]]);

        

        

        

        NSTimeInterval sc = [date timeIntervalSinceNow];

        NSDate *currentDate = [[NSDate alloc]initWithTimeIntervalSinceNow:sc];

        NSLog(@"%@",currentDate);

        

        

        //NSDate和字符串的转换

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

        df.dateFormat = @"yyyy-MM-dd hh:mm:ss";

        //[df setDateFormat:@"yyyy年MM月dd日  HH小时mm分ss秒"];

        NSString *na = [df stringFromDate:date];

        NSLog(@"系统当前时间为:%@",na);

        

        //取出日期中的年、月、日、时、分、秒

        NSCalendarDate *calendar = [NSCalendarDate calendarDate];

        int year = [calendar yearOfCommonEra];

        int month = [calendar monthOfYear];

        int day = [calendar dayOfMonth];

        NSLog(@"%4d-%02d-%02d",year,month,day);