过滤CoreData FetchRequest [英] Filtering a CoreData FetchRequest

问题描述

我正在尝试过滤fetchRequest。

I am having a brain meltdown trying to filter a fetchRequest.

我可以获得实体的每个记录的完整详细信息，但我只想

I'm able to get the full details of every record of the entity, but I only want the details on the record at the current indexPath.

这是我的代码目前所在的位置：

This is where my code is at present:

-(void) fetchStuff {

    NSLog(@"%s", __FUNCTION__); 
    NSError *error = nil;

    NSManagedObjectContext *context = [self managedObjectContext];      
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

    NSEntityDescription *woodgie = [NSEntityDescription entityForName:@"WidgetEntity" inManagedObjectContext:context];

    [fetchRequest setEntity:woodgie];

    NSArray *fetchResults = [managedObjectContext executeFetchRequest:fetchRequest error:&error];


    fetchedObjects = [fetchResults objectAtIndex:selectedRow];


    NSLog(@"selectedRow: %i", selectedRow);  //0

    NSLog(@"fetchedObjects: %@", fetchedObjects);



     for (WidgetEntity *wigglies in fetchedObjects  ) {

         NSSet *peopleSet = [wigglies valueForKey:@"people"];    
         for (id person in peopleSet) {          
             personName = [person valueForKey:@"name"];
             NSLog(@"name = %@", personName);
         }
         NSSet *keywordSet = [wigglies valueForKey:@"keyword"];  
         for (id keyWord in keywordSet) {
              keywordName = [keyWord valueForKey:@"word"];
             NSLog(@"Keyword = %@", keywordName);

.....
}

异常在此行​​for（WidgetEntity * wigglies in fetchedObjects）{
（countByEnumeratingWithState：objects：count：]：无法识别的选择器发送到实例）..

I get an exception at this line " for (WidgetEntity *wigglies in fetchedObjects ) {" (countByEnumeratingWithState:objects:count:]: unrecognized selector sent to instance)..

但是事实是 - 我想要如何过滤数据。

but the truth is - I'm guessing how to filter the data.

任何帮助/指针都会感激。

Any help / pointers will be appreciated.

推荐答案

您正在谈论获取已选择的行中的记录 - 这表明您已< >获取记录并显示它们，大概在表视图中。

You are talking about fetching the record in the "row that has been selected" - this suggests that you have already fetched the records and are displaying them, presumably in a table view.

在这种情况下，不需要重新获取实体，只需使用数据源数组或获取结果控制器中相应索引的对象。

In that case there is no need to re-fetch the entities, simply use the object from the appropriate index in your data source array or your fetched results controller.

这篇关于过滤CoreData FetchRequest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！