按周显示 NSDates [英] Display NSDates in terms of week

问题描述

场景:

我有一个费用跟踪 iOS 应用程序，我将费用从费用详细信息视图控制器存储到一个表视图(带有获取的结果控制器)中，该视图显示费用列表以及类别、金额和日期.我的实体Money"中确实有一个日期属性，它是支出或收入的父实体.

I have an expense tracking iOS Application and I am storing expenses from a expense detail view controller into a table view (with fetched results controller) that shows the list of expenses along with the category and amount and date. I do have a date attribute in my entity "Money" which is a parent entity for either an expense or an income.

问题:

我想要的是对给定的一周、一个月或一年的费用进行基本分类，并将其显示为部分标题，例如:(2012 年 10 月 1 日至 10 月 7 日)并显示费用金额和相关内容根据那个特定的星期.该视图中提供了两个按钮，如果我按下右按钮，它会将一周增加一周(2012 年 10 月 1 日至 10 月 7 日现在显示 2012 年 10 月 8 日至 15 日)，同样左按钮将减少一周一个星期.

What I want is to basically categorize my expenses for a given week, a month, or year and display it as the section header title for example : (Oct 1- Oct 7, 2012) and it shows expenses amount and related stuff according to that particular week. Two buttons are provided in that view, if I would press the right button, it will increment the week by a week (Oct 1- Oct 7, 2012 now shows Oct8 - Oct 15, 2012) and similarly the left button would decrement the week by a week.

我将如何做到这一点?我正在尝试以下代码 - 不起作用.

How would I accomplish that? I am trying the following code - doesn't work.

- (void)weekCalculation
{
   NSDate *today = [NSDate date];  // present date (current date)

   NSCalendar* calendar = [NSCalendar currentCalendar];
   NSDateComponents* comps = [calendar components:NSYearForWeekOfYearCalendarUnit |NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:today];

   [comps setWeekday:1]; // 1: Sunday
   firstDateOfTheWeek = [[calendar dateFromComponents:comps] retain];
   [comps setWeekday:7]; // 7: Saturday
   lastDateOfTheWeek = [[calendar dateFromComponents:comps] retain];

   NSLog(@" first date of week =%@", firstDateOfTheWeek);
   NSLog(@" last date of week =%@", lastDateOfTheWeek);

   firstDateOfWeek = [dateFormatter stringFromDate:firstDateOfTheWeek];
   lastDateOfWeek = [dateFormatter stringFromDate:lastDateOfTheWeek];

}

增加日期的代码 -

- (IBAction)showNextDates:(id)sender
{
   int addDaysCount = 7;

   NSDateComponents *dateComponents = [[[NSDateComponents alloc] init] autorelease];
   [dateComponents setDay:addDaysCount];

   NSDate *newDate1 = [[NSCalendar currentCalendar]
                    dateByAddingComponents:dateComponents
                    toDate:firstDateOfTheWeek options:0];

   NSDate *newDate2 = [[NSCalendar currentCalendar]
                    dateByAddingComponents:dateComponents
                    toDate:lastDateOfTheWeek options:0];

   NSLog(@" new dates =%@ %@", newDate1, newDate2);

}

假设一周显示如下(2012 年 11 月 4 日 - 2012 年 11 月 10 日)，我按下增量按钮，我在控制台中看到，日期更改为 2012 年 11 月 11 日和 2012 年 11 月 17 日，这是正确的，但如果我按再次点击增量按钮，它再次显示相同的日期(2012 年 11 月 11 日和 2012 年 11 月 17 日).

Suppose the week shows like this (Nov4, 2012 - Nov10, 2012) and I press the increment button, I see in the console, date changes to Nov11,2012 and Nov.17, 2012 which is right but if I press the increment button again, it shows the same date again (Nov 11, 2012 and Nov.17, 2012).

请帮帮我.

推荐答案

在您的班级中将 currentDate 声明为 @property.试试这个.

Declare currentDate as an @property in your class. And try this.

@property(nonatomic, retain) NSDate *currentDate;

初始设置

self.currentDate = [NSDate date];

在调用此方法之前.

- (void)weekCalculation
{
   NSCalendar* calendar = [NSCalendar currentCalendar];
   NSDateComponents* comps = [calendar components:NSYearForWeekOfYearCalendarUnit |NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:self.currentDate];

   [comps setWeekday:1]; // 1: Sunday
   firstDateOfTheWeek = [[calendar dateFromComponents:comps] retain];
   [comps setWeekday:7]; // 7: Saturday
   lastDateOfTheWeek = [[calendar dateFromComponents:comps] retain];

   NSLog(@" first date of week =%@", firstDateOfTheWeek);
   NSLog(@" last date of week =%@", lastDateOfTheWeek);

   firstDateOfWeek = [dateFormatter stringFromDate:firstDateOfTheWeek];
   lastDateOfWeek = [dateFormatter stringFromDate:lastDateOfTheWeek];

}

加载视图后，self.currentDate 值应从 showNextDates 更新.确保它不会在其他任何地方被重置.

Once the view is loaded self.currentDate value should be updated from showNextDates. Make sure it is not getting reset anywhere else.

- (IBAction)showNextDates:(id)sender
{
   int addDaysCount = 7;

   NSDateComponents *dateComponents = [[[NSDateComponents alloc] init] autorelease];
   [dateComponents setDay:addDaysCount];

   NSDate *newDate1 = [[NSCalendar currentCalendar]
                    dateByAddingComponents:dateComponents
                    toDate:firstDateOfTheWeek options:0];

   NSDate *newDate2 = [[NSCalendar currentCalendar]
                    dateByAddingComponents:dateComponents
                    toDate:lastDateOfTheWeek options:0];

   NSLog(@" new dates =%@ %@", newDate1, newDate2);

   self.currentDate = newDate1;

}

这篇关于按周显示 NSDates的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！