nsfetchedresultscontroller

问题 This is a follow up question to my previous question on: Core data: Managing employee contracts in a many-to-many relationship? There is a diagram on that question, and as a quick reminder there is the following: company --< contracts >-- employees I have been able to manually save 1 entity inside each of the entities, and verified them all in NSLog. I've created a CompanyListPage which lists all companies. The idea is that when you click on a company you will be presented with a list of all

问题 I am using a NSFetchedResultsController in combination with a UIManagedDocument which gets updated in an background thread. I have set up the NSFetchedResultsController exactly as described in this tutorial: How To Use NSFetchedResultsController I have set the delegate _fetchedResultsController.delegate = self and the protocol for my view controller to NSFetchedResultsControllerDelegate . My code works fine when it loads the data after launch. However, the NSFetchedResultsController does not

问题 I'm working on sorting NSFetchedResultController data. I need to sort data by their first name. However, there are some entries with no first name. I need the "no first name" objects to appear the bottom of the list, rather than the top. With the current code, when I sort the list by first name, the "no first name" cells are placed at the top. NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"Contacts"]; request.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:

问题 I have an UITableView populated by a NSFetchedResultsController . The initial fetch works fine. I can add, remove, modify, etc with zero problems.. But I want to add user-defined sorting to the table. I am doing this by changing the NSFetchedResultsController to use a different sortDescriptor set, and a different sectionNameKeyPath . Here is the code where I change the fetch: -(void)changeFetchData { fetchedResultsController = nil; NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

问题 In fetchedResultsController while setting the NSSortDescriptor iam getting this error unsupported NSSortDescriptor (comparator blocks are not supported) . NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Alarm" inManagedObjectContext: managedObjectContext]; [fetchRequest setEntity:entity]; //Below code is not working and causing error. sorting use the hours&seconds part of the time attribute NSSortDescriptor *sort

问题 I've been trying to build a Core Data stack as described by Marcus Zarra, where he has a Private Queue context and a Main Queue context (where the Main Queue context is a child of the Private Queue context). I believe I've correctly rebuilt (here) his described MCPersistenceController faithfully in Swift (the example code was Obj-C). The problem is in my ListViewModel class (which contains an NSFetchedResultsController ). No matter what I try, its delegate callbacks (

问题 I've been trying to build a Core Data stack as described by Marcus Zarra, where he has a Private Queue context and a Main Queue context (where the Main Queue context is a child of the Private Queue context). I believe I've correctly rebuilt (here) his described MCPersistenceController faithfully in Swift (the example code was Obj-C). The problem is in my ListViewModel class (which contains an NSFetchedResultsController ). No matter what I try, its delegate callbacks (

问题 Currently migrating to swift 3 and can't quite figure out what the parser wants for NSFetchedResultsController.deleteCache(withName: "rootCache") With this syntax, I'm getting a "Type 'String?' does not conform to protocol 'ExpressibleByStringLiteral'" error when building. 回答1: The error message is misleading. As of Swift 3, NSFetchedResultsController is a generic type open class NSFetchedResultsController<ResultType : NSFetchRequestResult> : NSObject { } and the following should work:

问题 Currently migrating to swift 3 and can't quite figure out what the parser wants for NSFetchedResultsController.deleteCache(withName: "rootCache") With this syntax, I'm getting a "Type 'String?' does not conform to protocol 'ExpressibleByStringLiteral'" error when building. 回答1: The error message is misleading. As of Swift 3, NSFetchedResultsController is a generic type open class NSFetchedResultsController<ResultType : NSFetchRequestResult> : NSObject { } and the following should work:

问题 I am using an NSFetchedResultsController to manage displaying fetched managed objects in a table view that has one section. The table starts out empty and the user can add new entities to it using the UI. As it stands, the program always works when adding the first entity, and always crashes when adding a second. There is sometimes no error presented upon the crash and other times there are errors of differing types (some included below). Through log statements and tracing I see that the