Core Data: fetch an NSManagedObject by its properties

Posted by niklassaers on Stack Overflow See other posts from Stack Overflow or by niklassaers
Published on 2010-05-13T13:20:29Z Indexed on 2010/05/13 13:24 UTC
Read the original article Hit count: 241

Filed under:

core-data

|

iphone-sdk

|

cocoa

|

cocoa-touch

Hi guys,

I have an object NetworkMember that has no attributes but is defined by its relationships Person, Network, Level and Role. In my app, I've found all the four relationships, but I want to make sure not to double-register my NetworkMember, thus I'd like to search for this NSManagedObject before instantiating it.

How should I write a query that queries for an NSManagedObject just consisting of relationships?

Cheers

Nik

© Stack Overflow or respective owner

Related posts about core-data

Records not being saved to core data sqlite file

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm a complete newbie when it comes to iOS programming and much less Core Data. It's rather non-intuitive for me, as I really came into my own with programming with MATLAB, which I guess is more of a 'scripting' language. At any rate, my problem is that I had no idea what I had to do to create a… >>> More
iPhone - Core Data crash on migration

as seen on Stack Overflow - Search for 'Stack Overflow'
I have problems, when i install app from Xcode all works but if I build app and install it from iTunes I have an error with the database at launch. This happens only than i have changes in the core data model and need to migrate to a new version. At first launch at crashes with message: Thread 0: 0… >>> More
CoreData update problems

as seen on Stack Overflow - Search for 'Stack Overflow'
My app makes updates in background thread then saves context changes. And in main context there is a table view that works with NSFetchedResultsController. For some time updates work correctly, but then exception is thrown. To check this I've added NSLog(@"%@", [self.controller fetchedObjects]); to… >>> More
Core Data managed object context thread synchronisation

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm have an issue where i'm updating a many-to-many relationship in a background thread, which works fine in that threa, but when I send the object back to the main thread the changes do not show. If I close the app and reopen the data is saved fine and the changes show on the main thread. Also using… >>> More
UITableView Core Data reordering

as seen on Stack Overflow - Search for 'Stack Overflow'
I know this question has been asked before, and I took a look at the answer to this question. However, I'm still confused as to how to implement reordering with a UITableView in a Core Data project. What I know is that I need to have a "displayOrder" attribute in my Entity to track the order of items… >>> More

Related posts about iphone-sdk

iPhone SDK 3.2 beta and iPhone SDK 3.1.2

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, Currently I am using iPhone SDK 3.1.2 for developing iPhone apps. Apple has recently released iPhone SDK 3.2 beta and I want to try my hands with it. But my problem is that I want to use both versions of SDKs, 3.1.2 since I am currently developing apps and uploading on app store, 3.2 beta… >>> More
iPhone SDK: subFolders inside the main bundle

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, in the current project I have a number of folders, with subfolders, and these contain images: 01.png, 02.png. Folder1/FolderA/f1.png Folder1/FolderB/F1.png When I compile the app, I looked inside the the .app and noticed that all the images are placed in the top level, with no sub-folders.… >>> More
accessing video preview data with iPhone SDK 3.1.2/3

as seen on Stack Overflow - Search for 'Stack Overflow'
Is there a way to access raw data of iphone camera preview? I mean not the data of the picture that was shot already, but the preview, that shows before taking a shot? TIA >>> More
iPhone SDK: subFolders inside the main bundle

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, in the current project I have a number of folders, with subfolders, and these contain images: 01.png, 02.png. Folder1/FolderA/f1.png Folder1/FolderB/F1.png When I compile the app, I looked inside the the .app and noticed that all the images are placed in the top level, with no sub-folders.… >>> More
Accessing Instance Attributes from Secondary Thread (iPhone-SDK)

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a class with an NSDictionary attribute. Inside this class I dispatch another thread to handle NSXMLParser handling. Inside my -didStartElement, I access the dictionary in the class (to compare an element found in the XML to one in the dictionary). At this point I get undefined results. Using… >>> More