从数据库中删除coredata并发出请求 [英] coredata-deleting from database and making request

问题描述

我是核心数据，所以我请求您的回答，我可以从具有以下功能的数据库中提取数据:

Hi I am a bit noob whit core-data so I request for your answer, I can pull out data from database whit this functions:

NSManagedObject *selectedObject = [[self fetchedResultsController]
    objectAtIndexPath:indexPath];
[[selectedObject valueForKey:@"SOMECOLLUMNNAME"] description];

但是我从数据库中删除时遇到了一个很大的问题，我已经读过我应该使用NSPredicate我读了

But I have a really big problems whit deleting from database I have read that I should use NSPredicate I read the tutorial but I do no figure out how can I write a simple

DELETE *
FROM Table t
WHERE t.date == 01.01.2011

例如.

您能帮我吗

推荐答案

嗯.我假设日期对象是NSString，而不是NSDate.

Hmm. I assume the date object is a NSString, not a NSDate.

尝试一下:

...// your code

NSPredicate * predicate = [NSPredicate predicateWithFormat:@"date == %@", @"01.01.2011"];

[request setPredicate:predicate];

// Execute the fetch -- create a mutable copy of the result.

NSError * error = nil;

NSMutableArray * mutableFetchResults = [[yourManagedObjectContext executeFetchRequest:request error:&error] mutableCopy];

for (int i = 0; i < [mutableFetchResults count]; i++)

{

   YourEntity * object = (YourEntity*)[mutableFetchResults objectAtIndex:i];

   [yourManagedObjectContext deleteObject:object];

}  

[mutableFetchResults release];

请问您是否需要更多帮助.

Pls ask if you need more help.

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