core-data NSDate搜索独特的天数和排序 [英] core-data NSDate searching for unique days and sorting

问题描述

关于NSDates有关该地方的大量信息，但我还没有找到一个明确的解决方案。

我有一个事件实体，每个实体具有潜在的许多 EventSessionTime 。

事件< --- >> EventSessionTime

在1表视图中我想显示一个唯一的日期列表，在 Events 想要显示特定日期的活动（按时间排序）。

为了实现这一点，我目前有2个NSDates - 一天一次和一些过于复杂的搜索/排序。

1）找到这些信息

2）查找特定日期的所有活动（此处重复此处）

$ b

感谢。

解决方案

我现在有以下关系。仍然有冗余的日期信息..

事件< --- >> EventSessionTime < < - > EventDay

UNIQUE days with events，no concern about specific time

我可以创建特定的日期，我知道时间。

  ... 
 [NSEntityDescription entityForName：@ EventSessionTimeinManagedObjectContext：self.managedObjectContext]; 
 ... 
 NSArray * res = [managedObjectContext executeFetchRequest：fetchRequest error：& error]; 
 [self myResultArray：[res valueForKeyPath：@@ distinctUnionOfObjects.eventDay.day]]; 
  

您可以推断我的属性和关系名称。

2）在特定日期查找所有活动（此处重复）

我使用以下谓词查找指定日期。它不会返回重复项_{（SUBQUERY（eventTime，$ x，$ x.eventDay.day =$））}

  [NSPredicate predicateWithFormat： =％@）。@ count> 0），<从上一个列表中选择的日期>]; 
  

Lots of information on NSDates about the place, but I haven't found a clear solution to this.

I have a list of Event entities, each with potentially many EventSessionTimes.

Event <--->> EventSessionTime

In 1 table view I want to display a unique list of days that have Events, in another table view I want to show the events on a particular day (ordered by time).

To achieve this I currently have 2 NSDates - a day and time - and some overly complicated searching/sorting. I want to remove this redundant information.

With that in mind, how can I:

1) Finding all UNIQUE days with events, no concern about specific time

2) Finding all EVENTS on a particular day (duplicates fine here)

Any tips on how to better achieve this would be great.

Thanks.

解决方案

I now have the following relationship. Still have redundant date information..

Event <--->> EventSessionTime <<--> EventDay

1) Finding all UNIQUE days with events, no concern about specific time

I can create specific dates where I know the time. The localised nature of my application means I can do this safely.

...
[NSEntityDescription entityForName:@"EventSessionTime" inManagedObjectContext:self.managedObjectContext];
...
NSArray *res = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
[self myResultArray:[res valueForKeyPath:@"@distinctUnionOfObjects.eventDay.day"]];

You can infer my attribute and relationship names.

2) Finding all EVENTS on a particular day (duplicates fine here)

I use the following predicate to find all events on the specified day with. It does not return duplicates

[NSPredicate predicateWithFormat: @"(SUBQUERY(eventTime, $x, $x.eventDay.day == %@).@count > 0)", <the day selected from the previous list>];

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