iPhone OS: Fetching a random entity instance using NSPredicate Nsfetchrequest and core data

Posted by nickthedude on Stack Overflow See other posts from Stack Overflow or by nickthedude
Published on 2010-05-13T21:42:42Z Indexed on 2010/05/13 21:44 UTC
Read the original article Hit count: 404

Filed under:

iphone

|

core-data

|

nspredicate

|

nsfetchrequest

Working on an app where I have a large collections of managed objects against which I want to fetch a few random instances.

My question is, is there any way I can use NSPredicate and NSFetchRequest to return several objects at random.

I saw that you could actually add a NSFetchRequest into the entity using the data modeler, any way to do the random fetch using this?

Also what would be the best method for determining the "count" of a table so I can set the bounds of the random number generator.

let me know if you need more details.

Thanks!

Nick

© Stack Overflow or respective owner

Related posts about iphone

iphone - direct link to iPhone review form from inside iphone

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to link directly to the review link of one of my Apps. I know that it is possible because Appirater did it in the past, but some change in iTunes turned the API down. Appirater uses this URL NSString *templateReviewURL = @"itms-apps://itunes.apple.com/WebObjects/MZStore.woa/wa/viewContentsUserReviews… >>> More
Buy iPhone 4 Without Contract: $599 (AT&T) and $699 (Verizon)

as seen on Tech Dreams - Search for 'Tech Dreams'
Purchasing iPhone without a contract is a good option when you are planning to gift it to someone or going to use it outside US. Both AT&T and Verizon lets you iPhone 4 without a contract but this information is buried deep under blurred text in FAQs and agreements. Here is the pricing… >>> More
Is it possible to download and run IPhone apps on an IPhone emulator

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am tasked to provide an IPhone client app for our SaaS website. I have never written an IPhone application, nor do I have an IPhone at the moment. Before I can decide whether or not I want to do this myself or outsource this, I'd like to try a few apps myself to get a feeling for the UI. Is… >>> More
iPhone web app from dashcode rss feed template works deployed on simulator but not on iphone

as seen on Stack Overflow - Search for 'Stack Overflow'
iPhone web app from dashcode rss feed template works deployed on simulator but not on iphone. The web app is deployed at; http://www.alila.se/wordpress/index.html If i run the simulator and enter that adress, it fetches the rss feed and displays it. Everything fine. When i enter the adress into… >>> More
Problem running iPhone application on iPhone from Xcode (and in Instruments)

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi I have a problem running one application on the iPhone from Xcode (or Instruments). When I try to run the app I get the error message Failed to upload XXX.app in the bottom left corner of Xcode. The strange thing is it actually uploaded the app to the iPhone but it doesn't start it (after this… >>> More

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