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POHow to use NSFetchedResultsController and UISearchDisplayController
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  1. POHow to use NSFetchedResultsController and UISearchDisplayController
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    copied!<p>I've been creating an iPhone App using Core Data.</p> <p>First of all, does it make sense to use an NSFetchedResultsController and a UISearchDisplayController together to fetch the result? Would you recommend something else?</p> <p>I've been trying quite long combining an NSFetchedResultController and a UISearchDisplayController. I've been thinking of setting an NSPredicate in the <code>(BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption</code> method to the NSFetchedResultController of the UIViewController. But this isn't working that well.</p> <p>So, have you any idea how to implement a solution for my problem? Thank you already for posting answers or links to good tutorials.</p> <p>EDIT</p> <p>Here is my code. The UISearchDisplayDelegate methods call the method <code>(void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope</code> that should set the predicate in the NSFetchedResultController. I've also added the code of the NSFetchedResultController.</p> <pre><code>- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString { [self filterContentForSearchText:searchString scope: [[self.searchDisplayController.searchBar scopeButtonTitles] objectAtIndex:[self.searchDisplayController.searchBar selectedScopeButtonIndex]]]; // Return YES to cause the search result table view to be reloaded. return YES; } - (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption { [self filterContentForSearchText:[self.searchDisplayController.searchBar text] scope: [[self.searchDisplayController.searchBar scopeButtonTitles] objectAtIndex:searchOption]]; // Return YES to cause the search result table view to be reloaded. return YES; } - (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope { NSString *query = self.searchDisplayController.searchBar.text; if (query &amp;&amp; query.length) { NSPredicate *predicate = [NSPredicate predicateWithFormat:@"Name contains[cd] %@", query]; [fetchedResultsController.fetchRequest setPredicate:predicate]; } NSError *error = nil; if (![[self fetchedResultsController] performFetch:&amp;error]) { // Handle error NSLog(@"Unresolved error %@, %@", error, [error userInfo]); exit(-1); // Fail } } - (NSFetchedResultsController *)fetchedResultsController { if (fetchedResultsController != nil) { return fetchedResultsController; } /* Set up the fetched results controller. */ // Create the fetch request for the entity. NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; // Edit the entity name as appropriate. NSEntityDescription *entity = [NSEntityDescription entityForName:@"Event" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; // Set the batch size to a suitable number. [fetchRequest setFetchBatchSize:20]; // Edit the sort key as appropriate. NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"timeStamp" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; // Edit the section name key path and cache name if appropriate. // nil for section name key path means "no sections". NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:@"Root"]; aFetchedResultsController.delegate = self; self.fetchedResultsController = aFetchedResultsController; [aFetchedResultsController release]; [fetchRequest release]; [sortDescriptor release]; [sortDescriptors release]; return fetchedResultsController; } </code></pre>
 

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