core-data

问题 I work with iPhone iOS 4.3. In my project I need a read-only, repopulated table of data (say a table with 20 rows and 20 fields). This data has to be fetched by key on the row. What is better approach? CoreData Archives, SQLite, or other? And how can I prepare and store this table? Thank you. 回答1: I would use core data for that. Drawback: You have to write a program (Desktop or iOS) to populate the persistent store. How to use a pre-populated store, you should have a look into the Recipes

问题 I have a table view backed up by core data with NSFetchedResultsController instance. This table has a search bar that displays filtered data. The search bar has a separate NSFetchedResultsController (FRC from now) instance. So far so good, the data is fetched and shown as expected in the table view and also shown correctly in the search bar's table view (when searching for data). My problem is that if I try to delete a cell in the search bar's table view then I get a coredata exception :

问题 I have a table view backed up by core data with NSFetchedResultsController instance. This table has a search bar that displays filtered data. The search bar has a separate NSFetchedResultsController (FRC from now) instance. So far so good, the data is fetched and shown as expected in the table view and also shown correctly in the search bar's table view (when searching for data). My problem is that if I try to delete a cell in the search bar's table view then I get a coredata exception :

问题 I've got a webservice returning me a JSON formatted string looking like this : {"id":4, "name":"name", "image":1, "contacts":[2,3] } Where the contacts array contains primary key to other objects. I tried doing my mapping in this way : RKManagedObjectMapping* mapping = [RKManagedObjectMapping mappingForClass:[OETGroup class] inManagedObjectStore:[RKObjectManager sharedManager].objectStore]; [mapping mapKeyPath:@"id" toAttribute:@"identifiant"]; [mapping mapKeyPath:@"name" toAttribute:@"name"]

问题 I've got a webservice returning me a JSON formatted string looking like this : {"id":4, "name":"name", "image":1, "contacts":[2,3] } Where the contacts array contains primary key to other objects. I tried doing my mapping in this way : RKManagedObjectMapping* mapping = [RKManagedObjectMapping mappingForClass:[OETGroup class] inManagedObjectStore:[RKObjectManager sharedManager].objectStore]; [mapping mapKeyPath:@"id" toAttribute:@"identifiant"]; [mapping mapKeyPath:@"name" toAttribute:@"name"]

问题 -objectWithID: is supposed to give me an object that's broken when the ID doesn't exist. The documentation says, that this object throws an exception when I try to access an property. However, it never throws any. Must I enable exceptions so that they're really thrown? Here's some code: // Assume: a new managed object has been created. Then it's ID has been converted to NSURL. // The MO has been saved. Then the NSURL has been converted back to an NSManagedObjectID *tmpID // So tmpID is an ID

问题 I have a simple Coredata model with one entity called "conversation" and the other one "messages". Basically, I need to kind of reproduce the iPhone sms application. I have a to-one relationship from message to conversation and a to-many from conversation to messages. Conversation{ messages<-->>Message.conversation } Message{ conversation<<-->Conversation.messages } Anytime I launch my app, all my conversation are loaded in my fetchedResultsController. If I understood correctly how Coredata

问题 "fetching ... " ... fetching what? Persistent objects? What's the scientific term when I send a request to an persistent store to get back an managed object? 回答1: You are fetching managed objects and their faults. 来源： https://stackoverflow.com/questions/2078222/how-is-the-process-called-when-getting-persistent-objects-out-of-the-persistent

问题 Is there any way I can skip dealing with NSNumber and work directly with NSInteger? 回答1: Core Data will only allow NSNumbers. However, you can write custom getters and setters to use NSInteger properties. mogenerator is a wonderful tool that does that automatically for you: it generates classes with native properties for all your entities. 回答2: No. NSInteger is just a typedef for a long integer, not an object. Actual implementation: #if __LP64__ || NS_BUILD_32_LIKE_64 typedef long NSInteger;

问题 The following code largely inspired by some example I found on the net seems to work fine, with the core data entity called "Contact" and the property called "address" having an attribute String, in the xcdatamodel. It saves my data with no problem. Now my question is : how do I need to modify this code ? In order to make it work after I change the attribute of the property "address" from String to Float in the xcdatamodel. CoreDataTestOneAppDelegate *appDelegate = [[UIApplication