代码之家 › 专栏 › 技术社区 › Guy

带搜索的nsfetchedresultsController

nsfetchedresultscontroller core-data objective-c

Guy · 技术社区 · 17 年前

过滤 NSFetchedResultsController 数据? 每次搜索栏的文本更改时是否需要重新初始化它?

我正在使用 UISearchDisplayControllers 我正在实施:

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString;

谢谢。

2 回复 | 直到 14 年前

Vincent Gable 14 年前

盖伊的答案和问题有什么不同?据我猜测,filterContentForsearchText:scope方法是由shouldReload方法调用的?

无论如何,这里有一些类似的代码,我在coredatabooks示例中添加了这些代码来包含搜索。在ib中为coredatabooks示例添加搜索显示控制器。然后我将代码添加到rootviewcontroller.m中,如下所示:

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString {
 NSInteger searchOption = controller.searchBar.selectedScopeButtonIndex;
 return [self searchDisplayController:controller shouldReloadTableForSearchString:searchString searchScope:searchOption];
}

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption {
 NSString* searchString = controller.searchBar.text;
 return [self searchDisplayController:controller shouldReloadTableForSearchString:searchString searchScope:searchOption];
}

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString*)searchString searchScope:(NSInteger)searchOption {

 NSPredicate *predicate = nil;
 if ([searchString length])
  if (searchOption == 0) // full text, in my implementation.  Other scope button titles are "Author", "Title"
   predicate = [NSPredicate predicateWithFormat:@"title contains[cd] %@ OR author contains[cd] %@", searchString, searchString];
  else
   // docs say keys are case insensitive, but apparently not so.
   predicate = [NSPredicate predicateWithFormat:@"%K contains[cd] %@", [[controller.searchBar.scopeButtonTitles objectAtIndex:searchOption] lowercaseString], searchString];
 [fetchedResultsController.fetchRequest setPredicate:predicate];

    NSError *error = nil;
    if (![[self fetchedResultsController] performFetch:&error]) {
  NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
  abort();
    }           

 return YES;
}

ps.要回答vivas,使用uisearchdisplaycontroller,它会自动创建一个新的表视图,用于覆盖筛选的列表。您可以检查文档中显示的正在使用哪个表视图,但在最简单的设置中,它只起作用,因为FetchedResultsController要么在搜索的表视图中显示筛选后的版本,要么在表视图中显示所有数据。

Alex Reynolds 16 年前

从表面上看,这是一个更好的方法:

- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
    self.savedSearchTerm = searchText;

    freshData = NO;
    if (searchText !=nil)
    {
            NSPredicate *predicate =[NSPredicate predicateWithFormat:@"name contains[cd] %@", searchText];
            [fetchedResultsController.fetchRequest setPredicate:predicate];
    }
    else
    {
            NSPredicate *predicate =[NSPredicate predicateWithFormat:@"All"];
            [fetchedResultsController.fetchRequest setPredicate:predicate];
    }

    NSError *error = nil;
    if (![[self fetchedResultsController] performFetch:&error]) {
            // Handle error
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            exit(-1);  // Fail
    }           

    [self.tableView reloadData];

    //    [searchBar resignFirstResponder];   
    //    [_shadeView setAlpha:0.0f];

 }