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 ...
I'm implementing iphone app with coredata functionality. I've an attribute in entity "NSDate" which stores the date and time when the record is added. I'm adding records at a faster rate. About 1 record per 25 milli seconds I want to store the date along with milli seconds so that I can retrieve the data in descending order. How can I do...
So i'm building a small application, it uses core data database of ~25mb size with 4 entities. It's for bus timetables. In one table named "Stop" there are ~1300 entries of bus stops with atributes "name", "id", "longitude", "latitude" and couple relationships. Now there are many stops with identical name attribute but different coordi...
I have a universal iPhone/iPad application that uses Core Data as storage. I would like to enable users to sync their data between two devices(iPhone , iPod and iPad). Is there any sample application or code that performs this? ...
So...I'm trying to get unit tests set up in my iPhone App but I'm having some issues. I'm trying to test my model classes but they inherit directly from NSManagedObject. I'm sure this is a problem but I don't know how to get around it. Everything is building and running as expected but I get this error when calling any method on the...
Hi, another iPhone newbie question... I have the following: NSPersistentStoreCoordinator NSManagedObjectContext NSManagedObjectModel Is it possible to run queries directly on the store (since its a sqlite DB)? I'm trying to delete all the records from a tableview, and figured a "DELETE FROM table" would be nice and quick as opposed t...
I display an image in a UIImageView (within a UIScrollView) which is also stored in CoreData. In the interface, I want the user to be able to rotate the picture by 90 degrees. I also want it to be saved in CoreData. What should I rotate in the display? the scrollview, the uiimageview or the image itself? (If possible I would like the r...
I have an iPhone/iPad app using Core Data to keep my application data. Sometimes, even though I don't get any error messages, the data is not really saved so when the app starts anew, it's all gone. This problem seems to disappear after physically rebooting the device, but otherwise it's pretty random and hard to track. Has anyone seen a...
I have a datamodel with to-many to-many relations. Using the example of employee database let say the entity division is related to department which in turn is related to employee. The employee has an attribute salary. How best to have a attribute at the level of division which is derived from the salary attribute. For example average sa...
I am working on an app that uses Core Data as its backend for managing SQLite records. I have everything working with strings and numbers, but have just tried adding BOOL fields and can't seem to get things to work. In the .xcdatamodel, I have added a field to my object called isCurrentlyForSale which is not Optional, not Transient, an...
I'm writing iphone app that has UITableView and uses Core Data. Data in UITableView is shown using NSFetchedResultsController. I use NSPredicate operator "IN" to fetch only needed entries. NSArray *filterArray = [NSArray arrayWithObjects:@"789", @"963", @"445", @"198", nil]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"i...
I am working on a project where I have a table view that is currently updated via a web request that returns XML. I implemented -(int)numberOfRowsInTableView:(NSTableView*)tv and -(id)tableView:(NSTableView *)tv objectValueForTableColumn:(NSTableColumn*)tableColumn row:(int)row in my XML parsing class, and have the table updated w...
I have a strange (to me) memory leak when accessing an entity in a relationship. Series and Tiles have an inverse relationship to each other. // set up the fetch request NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Series" inManagedObjectContext:managed...
Hi All, I have a Core Data-based iPhone app with a pre-populated read-only database. What protection (if any) can I apply to my database to reduce the likelihood of piracy / the database being read off a jail-broken iPhone? Most code examples for using a pre-populated sqlite database show the database being copied from the app bundle...
I tried to assign a managed object (C) with its property another managed object (B) (a one-to-one relationship) in which this other managed object (B) has a to-many relationship with one other managed object (A). There is an error from this assignment in which I copied as follows: #0 0x020e53a7 in ___forwarding___ #1 0x020c16c2 in __f...
When the following code is run on the iPhone the count of fetched objects after the delete is one less than before the delete. But on the iPad the count remains the same. This inconsistency was causing a crash on the iPad because elsewhere in the code, soon after the delete, fetchedObjects is called and the calling code, trusting the ...
I have a Core Data application which I plan to update with a new schema. The lightweight migration seems to work, but it takes time proportional to the amount of data in the database. This occurs in the didFinishLaunchingWithOptions phase of the app. I want to avoid <app> failed to launch in time problems, so I assume I cannot keep the ...
Ok so I'm trying to build this stat tracker for my app and I have built a data model object called statTracker that keeps track of all the stuff I want it to. I can set and retrieve values using the selectors, but if I try and use KVC (ie setValue: forKey: ) everything goes bad and says my StatTracker class is not KVC compliant: valueF...
Using Core Data w/a sqlite store on iPhone.... I've got a bunch of comic book image entities, each with a string that includes the comic's issue#, e.g.: image.imageTitle = @"Issue 12: Special Edition"; Part of the UI allows the user to type in an issue number to jump to the next issue. My initial code for this was sloooooooow because im...
I have Customer, Event and Address objects in my data model. Both Customer and Address have a one-to-many relationship to Event. I can get the distinct list of addresses for a customer's events for by doing this: NSSet *addressSet = [customer valueForKeyPath:@"events.address"]; For the part of the UI I'm working on now, I need to di...