如何使用UISearchDisplayController/UISearchBar过滤NSFetchedResultsController(CoreData)的内容

Question

如何使用UISearchDisplayController/UISearchBar过滤NSFetchedResultsController(CoreData)的内容

iphonesearchcore-datauisearchbaruisearchdisplaycontroller

149

我正在尝试在基于CoreData的iPhone应用程序中实现搜索代码。在更改太多代码之前，我想确保我走在正确的道路上。该应用程序已经拥有一个带有谓词的NSFetchedResultsController来检索主要TableView的数据。由于许多示例都是基于数组而不是CoreData，所以我感到困惑。

以下是一些问题：

1. 我是否需要另一个仅检索匹配项的NSFetchedResultsController，还是可以使用与主TableView相同的控制器？

2. 如果我使用相同的控制器，是否只需清除FRC缓存，然后在handleSearchForTerm：searchString方法中更改谓词即可？谓词是否必须包含初始谓词和搜索术语，或者它会记住首次检索数据时使用的谓词？

3. 如何返回原始结果？只需将搜索谓词设置为nil吗？这样做是否会破坏最初用于检索FRC结果的原始谓词？

如果有任何人有使用FRC进行搜索的代码示例，我将不胜感激！

- jschmidt

@Brent，完美的解决方案，对我非常有效！ - DetartrateD

11个回答

18

一些人评论说这可以用一个NSFetchedResultsController实现。我就是这么做的，以下是详细步骤。该解决方案假设您只想过滤表格并保持搜索结果的所有其他方面（排序顺序、单元格布局等）。

首先，在您的UITableViewController子类中定义两个属性（如果适用，请使用相应的@synthesize和dealloc）：

@property (nonatomic, retain) UISearchDisplayController *searchController;
@property (nonatomic, retain) NSString *searchString;

其次，在你的 UITableViewController 子类的 viewDidLoad: 方法中初始化搜索栏：

UISearchBar *searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0,0,self.tableView.frame.size.width,44)]; 
searchBar.placeholder = @"Search";
searchBar.delegate = self;
self.searchController = [[[UISearchDisplayController alloc] initWithSearchBar:searchBar contentsController:self] autorelease];
self.searchController.delegate = self;
self.searchController.searchResultsDataSource = self;   
self.searchController.searchResultsDelegate = self; 
self.tableView.tableHeaderView = self.searchController.searchBar;
[searchBar release];

第三步，按照以下方式实现UISearchDisplayController的代理方法：

// This gets called when you start typing text into the search bar
-(BOOL)searchDisplayController:(UISearchDisplayController *)_controller shouldReloadTableForSearchString:(NSString *)_searchString {
   self.searchString = _searchString;
   self.fetchedResultsController = nil;
   return YES;
}

// This gets called when you cancel or close the search bar
-(void)searchDisplayController:(UISearchDisplayController *)controller willUnloadSearchResultsTableView:(UITableView *)tableView {
   self.searchString = nil;
   self.fetchedResultsController = nil;
   [self.tableView reloadData];
}

最终，在fetchedResultsController方法中，根据是否定义了self.searchString，更改NSPredicate：

-(NSFetchedResultsController *)fetchedResultsController {
   if (fetchedResultsController == nil) {

       // removed for brevity

      NSPredicate *predicate;

      if (self.searchString) {
         // predicate that uses searchString (used by UISearchDisplayController)
         // e.g., [NSPredicate predicateWithFormat:@"name CONTAINS[cd] %@", self.searchString];
          predicate = ... 
      } else {
         predicate = ... // predicate without searchString (used by UITableViewController)
      }

      // removed for brevity

   }

   return fetchedResultsController;
}

- chris

1

这个解决方案对我非常有效，而且更加简单。谢谢！我只建议将'if (self.searchString)'微调为'if (self.searchString.length)'。这可以防止在开始搜索并从搜索栏中删除字符串后，若点击表视图会导致崩溃。 - Guto Araujo

17

我尝试了几次才使它工作...

我的理解关键在于意识到这里有两个tableView。一个由我的视图控制器管理，另一个由searchviewcontroller管理，然后我可以测试哪一个是活动的，并采取正确的操作。文档也很有帮助：

http://developer.apple.com/library/ios/#documentation/uikit/reference/UISearchDisplayController_Class/Reference/Reference.html

以下是我的做法 -

添加了searchIsActive标志：

@interface ItemTableViewController : UITableViewController <NSFetchedResultsControllerDelegate, UISearchDisplayDelegate, UISearchBarDelegate> {

    NSString *sectionNameKeyPath;
    NSArray *sortDescriptors;


@private
    NSFetchedResultsController *fetchedResultsController_;
    NSManagedObjectContext *managedObjectContext_;

    BOOL searchIsActive;

}

@property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;
@property (nonatomic, retain) NSFetchedResultsController *fetchedResultsController;
@property (nonatomic, retain) NSString *sectionNameKeyPath;
@property (nonatomic, retain) NSArray *sortDescriptors;
@property (nonatomic) BOOL searchIsActive;

在实现文件中添加了synthesize。

然后我添加了以下方法来进行搜索：

#pragma mark -
#pragma mark Content Filtering

- (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
{
    NSFetchRequest *aRequest = [[self fetchedResultsController] fetchRequest];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name BEGINSWITH[cd] %@", searchText];

    [aRequest setPredicate:predicate];

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

}

#pragma mark -
#pragma mark UISearchDisplayController Delegate Methods

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString
{
    [self filterContentForSearchText:[self.searchDisplayController.searchBar text] scope:nil];

    return YES;
}

/*
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption
{
    return YES;
}
*/

- (void)searchDisplayControllerWillBeginSearch:(UISearchDisplayController *)controller {
    [self setSearchIsActive:YES];
    return;
}

- (void)searchDisplayControllerDidEndSearch:(UISearchDisplayController *)controller 
{
    NSFetchRequest *aRequest = [[self fetchedResultsController] fetchRequest];

    [aRequest setPredicate:nil];

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

    [self setSearchIsActive:NO];
    return;
}

然后在 controllerWillChangeContent 方法中：

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller 
{
    if ([self searchIsActive]) {
        [[[self searchDisplayController] searchResultsTableView] beginUpdates];
    }
    else  {
        [self.tableView beginUpdates];
    }
}

并且 controllerDidChangeContent：

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller 
{
    if ([self searchIsActive]) {
        [[[self searchDisplayController] searchResultsTableView] endUpdates];
    }
    else  {
        [self.tableView endUpdates];
    }
}

当重置谓词时，删除缓存。

希望这可以帮助你。

- Rob Cohen

然而我还是不理解，上面的例子很好，但是不完整，但是你的建议应该是行得通的，但是它并没有起作用... - Vladimir Stazhilov

你可以直接检查活动表视图，而不是使用一个BOOL变量：if ( [self.tableView isEqual:self.searchDisplayController.searchResultsTableView] ) { ... } - rwyland

@rwyland - 我的测试显示，当搜索处于活动状态时，self.tableview未设置为searchdisplaycontroller.searchresultstableview。这些永远不会相等。 - giff

7

Swift 3.0、UISearchController、NSFetchedResultsController和Core Data

这段代码适用于 Swift 3.0 和 Core Data！你只需要一个单一的委托方法，以及几行代码来过滤和搜索模型中的对象。如果你已经实现了所有的FRC及其delegate方法以及searchController，那么就不需要任何其他操作。

UISearchResultsUpdating 协议方法

func updateSearchResults(for searchController: UISearchController) {

    let text = searchController.searchBar.text

    if (text?.isEmpty)! {
       // Do something 
    } else {
        self.fetchedResultsController.fetchRequest.predicate = NSPredicate(format: "( someString contains[cd] %@ )", text!)
    }
    do {
        try self.fetchedResultsController.performFetch()
        self.tableView.reloadData()
    } catch {}
}

就是这样！希望能对您有所帮助！谢谢

- Mannopson

5

您是否使用实时搜索？

如果没有，请使用数组（或NSFetchedResultsController）保存您之前使用的搜索内容，当用户按下“搜索”按钮时，将告诉FetchedResults更改其谓词。

无论哪种方法，每次都需要重新构建FetchedResults。我建议仅使用一个NSFetchedResultsController, 因为你需要重复很多代码并且不需要在未显示的内容中浪费内存。

只需确保有一个NSString“searchParameters”变量，并且您的FetchedResults方法会根据需要重新构建它，如果可用，则使用搜索参数，您应该只需执行以下操作：

a）将“searchParameters”设置为某个值（如果要获得所有结果，则为nil）。

b）释放并将当前的NSFetchedResultsController对象设置为nil。

c）重新加载表数据。

这是一个简单的代码示例：

- (void)searchString:(NSString*)s {
    self.searchResults = s;
    [fetchedResultsController release];
    fetchedResultsController = nil;
    [self.tableView reloadData];
}

-(NSFetchedResultsController *)fetchedResultsController {
    if (fetchedResultsController != nil) {
        return fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"EntityName" inManagedObjectContext:self.context];
    [fetchRequest setEntity:entity];

    [fetchRequest setFetchBatchSize:20];

    // searchResults is a NSString*
    if (searchResults != nil) {
        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name LIKE %@",searchResults];
        [fetchRequest setPredicate:predicate];
    }

    fetchedResultsController = 
    [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest 
        managedObjectContext:self.context sectionNameKeyPath:nil 
        cacheName:nil];
    fetchedResultsController.delegate = self;

    [fetchRequest release];

    return fetchedResultsController;    
}

- Sergio Moura

这似乎是有效的，但当您的表格由FRC填充时，它会失败。搜索表视图与您使用的主表视图不同。当在搜索并且主tableView想要重新加载单元格时，FRC代理方法在内存较低的设备上随处都会出现问题。 - Brent Priddy

有没有人有这个项目的模板链接？我发现很难弄清楚哪里应该放什么。有一个可用的模板作为参考会非常好。 - RyeMAC3

@Brent，你应该检查一下是否需要在FRC委托方法中更改搜索表格视图 - 如果你确实这样做了，并且在FRC和UITableView委托方法中更新了正确的表格视图，则使用FRC来处理主表格视图和搜索表格视图时一切都应该没问题。 - kervich

@kervich 我相信你在描述我上面的答案，还是说你能够只用一个FRC来完成它？ - Brent Priddy

@Brent，我只是想说，只要委托方法知道它们正在处理哪个UITableView，你就可以使用一个FRC完成它。事实上，当搜索栏内容被修改时，我使用一个FRC来显示列表并过滤它，只需更改NSPredicate即可。 - kervich

5

我面临着同样的任务，并找到了解决它的最简单方式。 简要地说：您需要定义另一种方法，与带有自定义复合谓词的-fetchedResultsController非常相似。

在我个人的情况下，我的-fetchedResultsController看起来像这样：

- (NSFetchedResultsController *) fetchedResultsController
{
    if (fetchedResultsController != nil)
    {
        return fetchedResultsController;
    }
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Client"
                                              inManagedObjectContext:[[PTDataManager sharedManager] managedObjectContext]];
    [fetchRequest setEntity:entity];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"agency_server_id == %@", agency.server_id];
    fetchRequest.predicate = predicate;

    NSSortDescriptor *sortByName1Descriptor = [[NSSortDescriptor alloc] initWithKey:@"lastname" ascending:YES];
    NSSortDescriptor *sortByName2Descriptor = [[NSSortDescriptor alloc] initWithKey:@"firstname" ascending:YES];
    NSSortDescriptor *sortByName3Descriptor = [[NSSortDescriptor alloc] initWithKey:@"middlename" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects: sortByName1Descriptor, sortByName2Descriptor, sortByName3Descriptor, nil];

    fetchRequest.sortDescriptors = sortDescriptors;

    fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest managedObjectContext:[[PTDataManager sharedManager] managedObjectContext] sectionNameKeyPath:nil cacheName:nil];
    fetchedResultsController.delegate = self;
    return fetchedResultsController;
}

如您所见，我正在获取一个机构的客户，并通过 agency.server_id 谓词进行过滤。结果，我将我的内容在一个 tableView 中检索出来（所有与 tableView 和 fetchedResultsController 代码相关的实现都是相当标准的）。为了实现 searchField ，我正在定义一个 UISearchBarDelegate 委托方法。我会用搜索方法触发它，比如 -reloadTableView：

- (void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
    [self reloadTableView];
}

当然还有-reloadTableView的定义：

- (void)reloadTableView
{
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Client"
                                              inManagedObjectContext:[[PTDataManager sharedManager] managedObjectContext]];
    [fetchRequest setEntity:entity];

    NSSortDescriptor *sortByName1Descriptor = [[NSSortDescriptor alloc] initWithKey:@"lastname" ascending:YES];
    NSSortDescriptor *sortByName2Descriptor = [[NSSortDescriptor alloc] initWithKey:@"firstname" ascending:YES];
    NSSortDescriptor *sortByName3Descriptor = [[NSSortDescriptor alloc] initWithKey:@"middlename" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects: sortByName1Descriptor, sortByName2Descriptor, sortByName3Descriptor, nil];
    fetchRequest.sortDescriptors = sortDescriptors;

    NSPredicate *idPredicate = [NSPredicate predicateWithFormat:@"agency_server_id CONTAINS[cd] %@", agency.server_id];
    NSString *searchString = self.searchBar.text;
    if (searchString.length > 0)
    {
        NSPredicate *firstNamePredicate = [NSPredicate predicateWithFormat:@"firstname CONTAINS[cd] %@", searchString];
        NSPredicate *lastNamePredicate = [NSPredicate predicateWithFormat:@"lastname CONTAINS[cd] %@", searchString];
        NSPredicate *middleNamePredicate = [NSPredicate predicateWithFormat:@"middlename CONTAINS[cd] %@", searchString];
        NSPredicate *orPredicate = [NSCompoundPredicate orPredicateWithSubpredicates:[NSArray arrayWithObjects:firstNamePredicate, lastNamePredicate, middleNamePredicate, nil]];
        NSPredicate *andPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:idPredicate, nil]];
        NSPredicate *finalPred = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:orPredicate, andPredicate, nil]];
        [fetchRequest setPredicate:finalPred];
    }
    else
    {
        [fetchRequest setPredicate:idPredicate];
    }

    self.fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest managedObjectContext:[[PTDataManager sharedManager] managedObjectContext] sectionNameKeyPath:nil cacheName:nil];
    self.fetchedResultsController.delegate = self;

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

    [self.clientsTableView reloadData];
}

这段代码与第一个“标准”的-fetchedResultsController非常相似，但是在if-else语句中，我们使用了以下方法：+andPredicateWithSubpredicates: - 使用此方法，我们可以设置一个谓词来保存我们主要的第一次获取的结果在tableView中。

+orPredicateWithSubpredicates - 使用此方法，我们通过来自searchBar的搜索查询来过滤现有的获取。

最后，我将谓词数组设置为此特定获取的复合谓词。对于必需的谓词使用AND，对于可选的谓词使用OR。

就是这样！你不需要再实现任何东西了。愉快的编码！

- Alex

1

使用CoreData对现有UITableView进行简单过滤的方法，且已按所需排序。

这个过程只需要花费我5分钟就能设置好并运行。

我已经有一个使用CoreData填充了来自iCloud的数据的现有UITableView，它具有相当复杂的用户交互，并且我不想为UISearchViewController复制所有内容。我可以简单地向FetchResultsController已使用的现有FetchRequest添加谓词，以过滤已排序的数据。

-(void)searchBar:(UISearchBar *)searchBar textDidChange:(NSString *)searchText
{
    NSPredicate *filterPredicate;

    if(searchText != nil && searchText.length > 0)
        filterPredicate = [NSPredicate predicateWithFormat:@"(someField CONTAINS[cd] %@) OR (someOtherField CONTAINS[cd] %@)", searchText, searchText];
    else
        filterPredicate = nil;

    _fetchedResultsController.fetchRequest.predicate = filterPredicate;

    NSError *error = nil;
    [_fetchedResultsController performFetch:&error];
    [self.tableView reloadData];
}

- Cliff Ribaudo

1

SWIFT 3.0

使用textField，由于iOS 8以后UISearchDisplayController已被弃用，您需要使用UISearchController。为什么不创建自己的搜索机制而不是处理搜索控制器呢？这样您可以自定义它并对其进行更多控制，而不必担心SearchController的变化和/或过时。

我使用的这种方法非常有效，并且不需要太多代码。但是，它需要您使用Core Data并实现NSFetchedResultsController。

首先，创建一个TextField并将其注册到一个方法中：

searchTextField?.addTarget(self, action: #selector(textFieldDidChange), for: UIControlEvents.editingChanged)

请创建您的textFieldDidChange方法，该方法在添加目标时已在选择器中描述：

func textFieldDidChange() {
    if let queryString = searchTextField.text {
        filterList(queryString)
        self.tableView.reloadData()
    }
}

然后，您希望使用NSPredicate或NSCompound Predicate（如果更复杂）在filterList()方法中过滤列表。在我的filterList方法中，我基于实体的名称和实体的“subCategories”对象的名称（一对多关系）进行过滤。

func filterList(_ queryString: String) {
    if let currentProjectID = Constants.userDefaults.string(forKey: Constants.CurrentSelectedProjectID) {
        if let currentProject = ProjectDBFacade.getProjectWithID(currentProjectID) {
            if (queryString != ""){
                let categoryPredicate = NSPredicate(format: "name CONTAINS[c] %@ && project == %@", queryString, currentProject)
                let subCategoryPredicate = NSPredicate(format: "subCategories.name CONTAINS[c] %@ && project == %@", queryString, currentProject)
                let orPredicate = NSCompoundPredicate(type: .or, subpredicates: [categoryPredicate, subCategoryPredicate])
                fetchedResultsController.fetchRequest.predicate = orPredicate
            }else{
                fetchedResultsController.fetchRequest.predicate = NSPredicate(format: "project == %@", currentProject)
            }

            do {
                try fetchedResultsController.performFetch()
            } catch {
                print("Error:  Could not fetch fetchedResultsController")
            }
        }
    }
}

- Josh O'Connor

0

这是一种处理具有多个数据集的fetchedResults的方法，既简单又通用，几乎可以应用于任何地方。只需在某些条件存在时将主结果抓取到数组中即可。

NSArray *results = [self.fetchedResultsController fetchedObjects];

通过循环遍历数组或者其他你想要的方式来查询它，以便创建你的主要fetchedResults的子集。现在当某些条件存在时，你可以使用完整的集合或子集。

- SmileBot

0

我非常喜欢@Josh O'Connor的方法，他不使用UISearchController。这个控制器仍然（Xcode 9）存在一个布局错误，许多人都在尝试解决它。

我已经恢复使用UISearchBar而不是UITextField，它工作得非常好。我的搜索/过滤要求是生成一个NSPredicate。这将传递给FRC：

   class ViewController: UIViewController, UITableViewDelegate, 
 UITableViewDataSource, UISearchBarDelegate {

        @IBOutlet var searchBar: UISearchBar!

         func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {

                shouldShowSearchResults = true

                if let queryString = searchBar.text {
                    filterList(queryString)

                    fetchData()
                }
            }



          func filterList(_ queryString: String) {
        if (queryString == "") {
            searchPredicate = nil
    }
        else {
            let brandPredicate = NSPredicate(format: "brand CONTAINS[c] %@", queryString)
            let modelPredicate = NSPredicate(format: "model CONTAINS[c] %@", queryString)
            let orPredicate = NSCompoundPredicate(type: .or, subpredicates: [brandPredicate, modelPredicate])
            searchPredicate = orPredicate
    }

}

...

let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
        let request = NSFetchRequest<NSFetchRequestResult>(entityName: filmEntity)
        request.returnsDistinctResults = true
        request.propertiesToFetch = ["brand", "model"]

        request.sortDescriptors = [sortDescriptor]
        request.predicate = searchPredicate

最后，将SearchBar连接到其委托。

希望这能帮助其他人。

- ICL1901

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- Brent Priddy · Accepted Answer

我最近在我的一个项目中实现了这个功能（你的问题和另一个错误答案提示了该怎么做）。我尝试了Sergio的答案，但在实际设备上运行时遇到了异常问题。

是的，您需要创建两个fetch结果控制器：一个用于正常显示，另一个用于UISearchBar的表视图。

如果您只使用一个FRC（NSFetchedResultsController），则原始的UITableView（而不是搜索期间活动的搜索表视图）可能会在搜索时调用回调并尝试错误地使用已过滤的版本。 FRC，您将看到有关节或行数不正确的异常抛出。

这是我所做的：我有两个FRC作为属性可用：fetchedResultsController和searchFetchedResultsController。仅在进行搜索时才应使用searchFetchedResultsController（当取消搜索时，可以看到此对象被释放）。所有的UITableView方法都必须确定它将查询哪个表视图以及从哪个适用的FRC中提取信息。FRC委托方法也必须确定要更新哪个tableView。

令人惊讶的是，其中有多少是样板代码。

头文件中相关的部分：

@interface BlahViewController : UITableViewController <UISearchBarDelegate, NSFetchedResultsControllerDelegate, UISearchDisplayDelegate> 
{
    // other class ivars

    // required ivars for this example
    NSFetchedResultsController *fetchedResultsController_;
    NSFetchedResultsController *searchFetchedResultsController_;
    NSManagedObjectContext *managedObjectContext_;

    // The saved state of the search UI if a memory warning removed the view.
    NSString        *savedSearchTerm_;
    NSInteger       savedScopeButtonIndex_;
    BOOL            searchWasActive_;
}
@property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;
@property (nonatomic, retain, readonly) NSFetchedResultsController *fetchedResultsController;

@property (nonatomic, copy) NSString *savedSearchTerm;
@property (nonatomic) NSInteger savedScopeButtonIndex;
@property (nonatomic) BOOL searchWasActive;

实现文件中相关部分：

@interface BlahViewController ()
@property (nonatomic, retain) NSFetchedResultsController *fetchedResultsController;
@property (nonatomic, retain) NSFetchedResultsController *searchFetchedResultsController;
@property (nonatomic, retain) UISearchDisplayController *mySearchDisplayController;
@end

我创建了一个有用的方法来检索正确的FRC，以便在处理所有UITableViewDelegate/DataSource方法时使用：

- (NSFetchedResultsController *)fetchedResultsControllerForTableView:(UITableView *)tableView
{
    return tableView == self.tableView ? self.fetchedResultsController : self.searchFetchedResultsController;
}

- (void)fetchedResultsController:(NSFetchedResultsController *)fetchedResultsController configureCell:(UITableViewCell *)theCell atIndexPath:(NSIndexPath *)theIndexPath
{
    // your cell guts here
}

- (UITableViewCell *)tableView:(UITableView *)theTableView cellForRowAtIndexPath:(NSIndexPath *)theIndexPath
{
    CallTableCell *cell = (CallTableCell *)[theTableView dequeueReusableCellWithIdentifier:@"CallTableCell"];
    if (cell == nil) 
    {
        cell = [[[CallTableCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:@"CallTableCell"] autorelease];
    }

    [self fetchedResultsController:[self fetchedResultsControllerForTableView:theTableView] configureCell:cell atIndexPath:theIndexPath];
    return cell;
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{
    NSInteger count = [[[self fetchedResultsControllerForTableView:tableView] sections] count];

    return count;
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{
    NSInteger numberOfRows = 0;
    NSFetchedResultsController *fetchController = [self fetchedResultsControllerForTableView:tableView];
    NSArray *sections = fetchController.sections;
    if(sections.count > 0) 
    {
        id <NSFetchedResultsSectionInfo> sectionInfo = [sections objectAtIndex:section];
        numberOfRows = [sectionInfo numberOfObjects];
    }

    return numberOfRows;

}

搜索栏的委托方法：

#pragma mark -
#pragma mark Content Filtering
- (void)filterContentForSearchText:(NSString*)searchText scope:(NSInteger)scope
{
    // update the filter, in this case just blow away the FRC and let lazy evaluation create another with the relevant search info
    self.searchFetchedResultsController.delegate = nil;
    self.searchFetchedResultsController = nil;
    // if you care about the scope save off the index to be used by the serchFetchedResultsController
    //self.savedScopeButtonIndex = scope;
}


#pragma mark -
#pragma mark Search Bar 
- (void)searchDisplayController:(UISearchDisplayController *)controller willUnloadSearchResultsTableView:(UITableView *)tableView;
{
    // search is done so get rid of the search FRC and reclaim memory
    self.searchFetchedResultsController.delegate = nil;
    self.searchFetchedResultsController = nil;
}

- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString
{
    [self filterContentForSearchText:searchString 
                               scope:[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 selectedScopeButtonIndex]];

    // Return YES to cause the search result table view to be reloaded.
    return YES;
}

在从FRC委托方法获取更新时，请确保使用正确的表视图：

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller 
{
    UITableView *tableView = controller == self.fetchedResultsController ? self.tableView : self.searchDisplayController.searchResultsTableView;
    [tableView beginUpdates];
}


- (void)controller:(NSFetchedResultsController *)controller 
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex 
     forChangeType:(NSFetchedResultsChangeType)type 
{
    UITableView *tableView = controller == self.fetchedResultsController ? self.tableView : self.searchDisplayController.searchResultsTableView;

    switch(type) 
    {
        case NSFetchedResultsChangeInsert:
            [tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}


- (void)controller:(NSFetchedResultsController *)controller 
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)theIndexPath 
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath 
{
    UITableView *tableView = controller == self.fetchedResultsController ? self.tableView : self.searchDisplayController.searchResultsTableView;

    switch(type) 
    {
        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:theIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self fetchedResultsController:controller configureCell:[tableView cellForRowAtIndexPath:theIndexPath] atIndexPath:theIndexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:theIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller 
{
    UITableView *tableView = controller == self.fetchedResultsController ? self.tableView : self.searchDisplayController.searchResultsTableView;
    [tableView endUpdates];
}

其他视图信息：

- (void)loadView 
{   
    [super loadView];
    UISearchBar *searchBar = [[[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, self.tableView.frame.size.width, 44.0)] autorelease];
    searchBar.autoresizingMask = (UIViewAutoresizingFlexibleWidth);
    searchBar.autocorrectionType = UITextAutocorrectionTypeNo;
    self.tableView.tableHeaderView = searchBar;

    self.mySearchDisplayController = [[[UISearchDisplayController alloc] initWithSearchBar:searchBar contentsController:self] autorelease];
    self.mySearchDisplayController.delegate = self;
    self.mySearchDisplayController.searchResultsDataSource = self;
    self.mySearchDisplayController.searchResultsDelegate = self;
}

- (void)didReceiveMemoryWarning
{
    self.searchWasActive = [self.searchDisplayController isActive];
    self.savedSearchTerm = [self.searchDisplayController.searchBar text];
    self.savedScopeButtonIndex = [self.searchDisplayController.searchBar selectedScopeButtonIndex];

    fetchedResultsController_.delegate = nil;
    [fetchedResultsController_ release];
    fetchedResultsController_ = nil;
    searchFetchedResultsController_.delegate = nil;
    [searchFetchedResultsController_ release];
    searchFetchedResultsController_ = nil;

    [super didReceiveMemoryWarning];
}

- (void)viewDidDisappear:(BOOL)animated
{
    // save the state of the search UI so that it can be restored if the view is re-created
    self.searchWasActive = [self.searchDisplayController isActive];
    self.savedSearchTerm = [self.searchDisplayController.searchBar text];
    self.savedScopeButtonIndex = [self.searchDisplayController.searchBar selectedScopeButtonIndex];
}

- (void)viewDidLoad
{
    // restore search settings if they were saved in didReceiveMemoryWarning.
    if (self.savedSearchTerm)
    {
        [self.searchDisplayController setActive:self.searchWasActive];
        [self.searchDisplayController.searchBar setSelectedScopeButtonIndex:self.savedScopeButtonIndex];
        [self.searchDisplayController.searchBar setText:savedSearchTerm];

        self.savedSearchTerm = nil;
    }
}

FRC创建代码：

- (NSFetchedResultsController *)newFetchedResultsControllerWithSearch:(NSString *)searchString
{
    NSArray *sortDescriptors = // your sort descriptors here
    NSPredicate *filterPredicate = // your predicate here

    /*
     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 *callEntity = [MTCall entityInManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:callEntity];

    NSMutableArray *predicateArray = [NSMutableArray array];
    if(searchString.length)
    {
        // your search predicate(s) are added to this array
        [predicateArray addObject:[NSPredicate predicateWithFormat:@"name CONTAINS[cd] %@", searchString]];
        // finally add the filter predicate for this view
        if(filterPredicate)
        {
            filterPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:[NSArray arrayWithObjects:filterPredicate, [NSCompoundPredicate orPredicateWithSubpredicates:predicateArray], nil]];
        }
        else
        {
            filterPredicate = [NSCompoundPredicate orPredicateWithSubpredicates:predicateArray];
        }
    }
    [fetchRequest setPredicate:filterPredicate];

    // Set the batch size to a suitable number.
    [fetchRequest setFetchBatchSize:20];

    [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:self.managedObjectContext 
                                                                                                  sectionNameKeyPath:nil 
                                                                                                           cacheName:nil];
    aFetchedResultsController.delegate = self;

    [fetchRequest release];

    NSError *error = nil;
    if (![aFetchedResultsController performFetch:&error]) 
    {
        /*
         Replace this implementation with code to handle the error appropriately.

         abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
         */
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return aFetchedResultsController;
}    

- (NSFetchedResultsController *)fetchedResultsController 
{
    if (fetchedResultsController_ != nil) 
    {
        return fetchedResultsController_;
    }
    fetchedResultsController_ = [self newFetchedResultsControllerWithSearch:nil];
    return [[fetchedResultsController_ retain] autorelease];
}   

- (NSFetchedResultsController *)searchFetchedResultsController 
{
    if (searchFetchedResultsController_ != nil) 
    {
        return searchFetchedResultsController_;
    }
    searchFetchedResultsController_ = [self newFetchedResultsControllerWithSearch:self.searchDisplayController.searchBar.text];
    return [[searchFetchedResultsController_ retain] autorelease];
}