我正在使用Core Data创建iPhone应用程序。
首先，同时使用NSFetchedResultsController和UISearchDisplayController获取结果是有意义的吗？您会推荐其他东西吗？
我已经尝试了相当长时间将NSFetchedResultController和UISearchDisplayController组合在一起。我一直在考虑在UIViewController的NSFetchedResultController中的(BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption方法中设置NSPredicate。但这并没有很好地工作。
那么，您是否有想法如何为我的问题实现解决方案？感谢您提供答案或链接到好的教程。
编辑：
这是我的代码。 UISearchDisplayDelegate方法调用(void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope方法，该方法应在NSFetchedResultController中设置谓词。 我还添加了NSFetchedResultController的代码。
- (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 && query.length) {
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"Name contains[cd] %@", query];
[fetchedResultsController.fetchRequest setPredicate:predicate];
}
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&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;
}