Question

我有一个带有联系人的表格视图。当我选择联系人必须添加到另一个表：RecentsTable时。最近访问的项目。为了这个目的，我使用了这样的代码，它正在工作但是。在昨天的情况下，它被认为是24小时。但是，当日期改变时，我想显示昨天的项目，然后自动将它添加到昨天的列表中。请指导我。

     NSDate *date = self.lastviewed;
                double time = [date timeIntervalSinceNow];

                NSString *tmpValue = nil;
                time *= -1;


                if(time < 3600*24) {
                    tmpValue = @"Today";
                }

                else {
                    int div = round(time / 60 / 60 / 24);

             // I want solution wth respect to yesterday's date date but not as follows
                     if(div == 1)
                          tmpvalue = @ "Yester Day";


                if (div >1 && div <7)
                        //tmpValue= [NSString stringWithFormat:@"%d days ago", div];
                        tmpValue = @"This Week";

                    else if(div <30)
                        tmpValue = @"This Month";
                    else 
                        tmpValue = @"Earlier"; 
                }

提前感谢..

Answer 1

使用日期时，您应该使用NSDateComponents。它将处理日光节省等问题。在NSDate上有很多关于StackOverflow的问题，例如this one可以通过将日期组件更改为-1天来解决您的问题。

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *today = [NSDate date];

NSDateComponents *dayComponent = [[NSDateComponents alloc] init];
dayComponent.day = -1;
NSDate *yesterday = [gregorian dateByAddingComponents:dayComponent 
                                               toDate:today 
                                              options:0];

Answer 2

我认为您不仅要更改“昨天”案例，还要更改月，年和周的其他计算。

NSDate *date = self.lastviewed;
// double time = [date timeIntervalSinceNow];
NSCalendar *currentCalendar = [NSCalendar currentCalendar];
NSDateComponents * componentsOfDate = [currentCalendar 
                                        components: (NSYearCalendarUnit|NSMonthCalendarUnit|
                                                   NSDayCalendarUnit|NSWeekCalendarUnit)
                                       fromDate:date];
NSDateComponents * componentsOfToday = [currentCalendar 
                                         components:(NSYearCalendarUnit|NSMonthCalendarUnit|
                                         NSDayCalendarUnit|NSWeekCalendarUnit) 
                                       fromDate:[NSDate date]];

if ([componensOfDate year] == [componentsOfToday year])
    if ([componentsOfDate month] == [componentsOfToday month])
        if([componentsOfDate day] == [componentsOfToday day])
            tmpvalue = @"Today" ;
         else
             tmpvalue = @"This Month" ;
    else
        tmpvalue = @"This Year" ;

// This week calculation, the easy way.
if([componentsOfDate week] == [componentsOfToday week] && 
   abs([date timeIntervalSinceNow]) <= (7*24*60*60))
    tmpvalue = @"This Week" ;

// Yesterday calculation
NSDate * yesterday = [NSDate dateWithTimeInterval:(-24*7*60*60) sinceDate:[NSDate date]];
NSComponents *componentsOfYesterday = [currentCalendar 
                                        components: (NSYearCalendarUnit|NSMonthCalendarUnit|
                                                   NSDayCalendarUnit)
                                       fromDate:yesterday];

// check this, as I'm not sure you can use compare: on components object
if([componentsOfDate compare:componentsOfYesterday] == NSOrderedSame)
  tmpvalue = @"Yesterday";

Answer 3

如果您使用NSCalendar获取日期和月份单位会更容易。

有关示例，请参阅this和this。

如果您获得当天和给定的lastViewed日的日，月单位，您可以通过比较两者来找到所需的值。

修改

NSDate *todate = [NSDate date]; NSDate *lastViewedDate = self.lastviewed; NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; NSUInteger unitFlags = NSMonthCalendarUnit | NSDayCalendarUnit; NSDateComponents *components = [gregorian components:unitFlags fromDate:lastViewedDate toDate:todate options:0]; NSInteger months = [components month]; NSInteger days = [components day]; NSString *tmpValue = nil; if ( days == 0 ) { tmpValue = @"Today"; } else { if(days == 1) tmpValue = @"Yesterday"; else if (days >1 && days <7) //tmpValue= [NSString stringWithFormat:@"%d days ago", div]; tmpValue = @"This Week"; else if(days <30) tmpValue = @"This Month"; else tmpValue = @"Earlier"; }

如何显示yesterDay（相对于日期，但不是24小时的时间间隔）访问iPhone目标c中的项目

3 个答案: