删除部分的最后一行后，应用程序崩溃
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【中文标题】删除部分的最后一行后，应用程序崩溃【英文标题】：After deleting last row of a section, the app crashes 【发布时间】：2013-11-29 21:59:35 【问题描述】：在我的 ios 应用程序中，我有一个包含部分的表格视图，所有部分都由核心数据填充。 如果删除部分的最后一行，则应用程序崩溃。 我无法找出我的代码中的问题所在，请您帮助我。先感谢您。到目前为止，这是我的代码：
#import "PersonsTVC.h"
#import "Person.h"
@implementation PersonsTVC
@synthesize fetchedResultsController = __fetchedResultsController;
@synthesize managedObjectContext = __managedObjectContext;
@synthesize selectedPerson;
@synthesize searchResults,titulosseccion;
- (void)setupFetchedResultsController
// 1 - Decide what Entity you want
NSString *entityName = @"Person"; // Put your entity name here
NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName);
// 2 - Request that Entity
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];
// 3 - Filter it if you want
//request.predicate = [NSPredicate predicateWithFormat:@"Person.name = Blah"];
// 4 - Sort it if you want
// First sort descriptor (required for grouping into sections):
NSSortDescriptor *sortByDate = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:NO];
// Second sort descriptor (for the items within each section):
NSSortDescriptor *sortByName = [[NSSortDescriptor alloc] initWithKey:@"firstname" ascending:YES];
[request setSortDescriptors:@[sortByDate, sortByName]];
//
// request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"firstname"
//ascending:YES
//selector:@selector(localizedCaseInsensitiveCompare:)]];
// 5 - Fetch it
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:@"sectionIdentifier"
cacheName:nil];
[self performFetch];
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
id <NSFetchedResultsSectionInfo> theSection = [[self.fetchedResultsController sections] objectAtIndex:section];
NSString *sectionName = [theSection name];
if ([sectionName isEqualToString:@"0"])
return @"Today";
else if ([sectionName isEqualToString:@"1"])
return @"Tomorrow";
else if ([sectionName isEqualToString:@"2"])
return @"Upcoming";
return @"Other";
- (NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
// Return the number of sections.
return [[self.fetchedResultsController sections] count];
- (void) viewDidLoad
self.searchResults = [NSMutableArray arrayWithCapacity:[[self.fetchedResultsController fetchedObjects] count]];
[self.tableView reloadData];
- (void)viewWillAppear:(BOOL)animated
[super viewWillAppear:animated];
[self setupFetchedResultsController];
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
// Perform segue to detail when a SEARCH table cell is touched
if(tableView == self.searchDisplayController.searchResultsTableView)
[self performSegueWithIdentifier:@"Person Detail Segue" sender:tableView];
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
static NSString *CellIdentifier = @"Persons Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
// Configure the cell...
// Configure the cell...
Person *person = nil;
if (tableView == self.searchDisplayController.searchResultsTableView)
NSLog(@"Configuring cell to show search results");
person = [self.searchResults objectAtIndex:indexPath.row];
else
NSLog(@"Configuring cell to show normal data");
person = [self.fetchedResultsController objectAtIndexPath:indexPath];
NSString *fullname = [NSString stringWithFormat:@"%@ %@", person.firstname, person.surname];
cell.textLabel.text = person.firstname;
if ([person.inRole.color isEqual :@"Yellow"])
cell.imageView.image = [UIImage imageNamed:@"Yellow"];
if ([person.inRole.color isEqual :@"Black"])
cell.imageView.image = [UIImage imageNamed:@"Black"];
if ([person.inRole.color isEqual :@"Grey"])
cell.imageView.image = [UIImage imageNamed:@"Grey"];
if ([person.inRole.color isEqual :@"Red"])
cell.imageView.image = [UIImage imageNamed:@"Red"];
if ([person.inRole.color isEqual :@"Blue"])
cell.imageView.image = [UIImage imageNamed:@"Blue"];
if ([person.inRole.color isEqual :@"Dark Green"])
cell.imageView.image = [UIImage imageNamed:@"DarkGreen"];
if ([person.inRole.color isEqual :@"Light Green"])
cell.imageView.image = [UIImage imageNamed:@"LightGreen"];
if ([person.inRole.color isEqual :@"Light Blue"])
cell.imageView.image = [UIImage imageNamed:@"LightBlue"];
if ([person.inRole.color isEqual :@"Brown"])
cell.imageView.image = [UIImage imageNamed:@"Brown"];
if ([person.inRole.color isEqual :@"Dark Orange"])
cell.imageView.image = [UIImage imageNamed:@"DarkOrange"];
NSDate *fechasinformat = person.date;
NSString *fecha0 = [NSString stringWithFormat:@"%@", fechasinformat];
cell.detailTextLabel.text = fecha0;
return cell;
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
if (tableView == self.searchDisplayController.searchResultsTableView)
return [self.searchResults count];
else
return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
if (editingStyle == UITableViewCellEditingStyleDelete)
[self.tableView beginUpdates]; // Avoid NSInternalInconsistencyException
// Delete the person object that was swiped
Person *personToDelete = [self.fetchedResultsController objectAtIndexPath:indexPath];
NSLog(@"Deleting (%@)", personToDelete.firstname);
[self.managedObjectContext deleteObject:personToDelete];
[self.managedObjectContext save:nil];
// Delete the (now empty) row on the table
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[self performFetch];
[self.tableView endUpdates];
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
if ([segue.identifier isEqualToString:@"Add Person Segue"])
NSLog(@"Setting PersonsTVC as a delegate of PersonDetailTVC");
PersonDetailTVC *personDetailTVC = segue.destinationViewController;
personDetailTVC.delegate = self;
NSLog(@"Creating a new person and passing it to PersonDetailTVC");
Person *newPerson = [NSEntityDescription insertNewObjectForEntityForName:@"Person"
inManagedObjectContext:self.managedObjectContext];
personDetailTVC.person = newPerson;
else if ([segue.identifier isEqualToString:@"Person Detail Segue"])
NSLog(@"Setting PersonsTVC as a delegate of PersonDetailTVC");
PersonDetailTVC *personDetailTVC = segue.destinationViewController;
personDetailTVC.delegate = self;
// Store selected Person in selectedPerson property
if(sender == self.searchDisplayController.searchResultsTableView)
NSIndexPath *indexPath = [self.searchDisplayController.searchResultsTableView indexPathForSelectedRow];
self.selectedPerson = [self.searchResults objectAtIndex:[indexPath row]];
else
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
self.selectedPerson = [self.fetchedResultsController objectAtIndexPath:indexPath];
NSLog(@"Passing selected person (%@) to PersonDetailTVC", self.selectedPerson.firstname);
personDetailTVC.person = self.selectedPerson;
else
NSLog(@"Unidentified Segue Attempted!");
- (void)theSaveButtonOnThePersonDetailTVCWasTapped:(PersonDetailTVC *)controller
// do something here like refreshing the table or whatever
// close the delegated view
[controller.navigationController popViewControllerAnimated:YES];
#pragma mark -
#pragma mark Content Filtering
-(void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
self.searchResults = [[self.fetchedResultsController fetchedObjects] filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id evaluatedObject, NSDictionary *bindings)
Person* person = evaluatedObject;
NSString* firstName = person.firstname;
//searchText having length < 3 should not be considered
if (!!searchText && [searchText length] < 3)
return YES;
if ([scope isEqualToString:@"All"] || [firstName isEqualToString:scope])
return ([firstName rangeOfString:searchText].location != NSNotFound);
return NO; //if nothing matches
]];
#pragma mark -
#pragma mark UISearchDisplayController Delegate Methods
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString
[self filterContentForSearchText:searchString scope:@"All"];
return YES;
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchScope:(NSInteger)searchOption
[self filterContentForSearchText:[self.searchDisplayController.searchBar text] scope:@"All"];
return YES;
@end
【问题讨论】：
这是错误日志：由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“无效更新：无效的节数。更新后表视图中包含的节数（1）必须等于更新前表视图中包含的节数（1），加上或减去插入或删除的节数（0插入，1已删除）。' 你实现了 fetchedResultsController 委托方法吗？如果不这样做，让他们处理任何 UITableView 更新。 嗨，邓肯，我不知道该怎么做....谢谢 阅读此developer.apple.com/library/ios/documentation/CoreData/… 感谢 Duncan，我已阅读文档，但我没有经验知道如何实施所有这些信息，无论如何，谢谢... 【参考方案1】：错误清楚地表明您删除了 1 个部分，删除前有 1 个，删除后有 1 个。这就是问题。所以可能你的
- (NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
删除最后一个对象后返回不正确的节数。
在删除最后一个对象后，您的 [[self.fetchedResultsController sections] count] 不为 0，或者 numberOfSectionsInTableView:(UITableView *)tableView 被 self.searchDisplayController.searchResultsTableView 调用，而您没有进行检查。
编辑：要解决此问题，请添加以下代码：
- (NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
// Return the number of sections.
if(tableView==self.searchDisplayController.searchResultsTableView)
NSLog("search table asking");
else
NSLog("main table asking");
NSLog("fetched sections: %d", [[self.fetchedResultsController sections] count]);
return [[self.fetchedResultsController sections] count];
并在崩溃发生时发布控制台输出。
【讨论】：
谢谢@GWiz，我能做些什么来解决这个问题？你会帮我吗？ 我更正了我的编辑，以确保我们知道哪个表正在“询问”其节数 谢谢@gWiz，我现在必须去一段时间，回来我会告诉你它是如何工作的。再次感谢您。 应用崩溃后显示第二个NSLog，添加一行后显示：fetchedsections:1，删除后：fetchedsections:0 崩溃前是否显示“搜索表询问”或“主表询问”？【参考方案2】：要实现 NSFetchedResultsController 委托方法，请将以下代码添加到您的 viewController（我删除了一些代码以便检查它是否编译），并在创建控制器时使用 _fetchedResultsController.delegate = self; 之类的东西将 viewController 设置为委托（在 setupFetchedResultsController 中） .
只要添加、修改或删除 fetchedResultsController 结果集中的 managedObjects，就会调用这些方法。您可以看到它们包含对 UITableView 的必要调用以更新显示。这些与使用 fetchedResultsController 作为 UITableView 的数据源一起使用 - 这样您就不会遇到任何不一致的错误。
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
NSLog(@"controllerWillChangeContent: called");
[self.tableView beginUpdates];
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
NSLog(@"didChangeSection: called");
switch(type)
case NSFetchedResultsChangeInsert:
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
NSLog(@"controller:didChangeObject: called");
NSLog(@" object is %@", [anObject valueForKey:@"displayName"]);
UITableView *tableView = self.tableView;
switch(type)
case NSFetchedResultsChangeInsert:
NSLog(@"NSFetchedResultsChangeInsert: called");
[tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
NSLog(@"NSFetchedResultsChangeDelete: called");
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
NSLog(@"NSFetchedResultsChangeUpdate: called");
[self configureCell:tableView cell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
break;
case NSFetchedResultsChangeMove:
NSLog(@"NSFetchedResultsChangeMove: called");
self.changedObjectIndex = newIndexPath;
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
// NOTE: This is overridden by subclasses to modify the default behaviour
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
NSLog(@“controllerDidChangeContent: called");
[self.tableView endUpdates];
- (void)configureCell:(UITableView *)tableView cell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
NSManagedObject *object;
object = [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = [[object valueForKey:@"displayName"] description];
bool found =[[object valueForKey:@"found"] boolValue];
if (found)
cell.textLabel.textColor = [UIColor greenColor];
【讨论】：
【参考方案3】：适当的解决方案是让您的PersonsTVC 成为获取结果控制器的代表。
如果您打开一个使用 CoreData 的空项目，您将有更好的理解，并且可能会找到您尝试完成的解决方案。
您的代码应该是最简单的形式：
- (void)setupFetchedResultsController
//Setup your fetch request ...
NSFetchedResultsController* controller =
[[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:@"sectionIdentifier"
cacheName:nil];
//setup the delegation and retain the FRC
controller.delegate = self;
self.fetchedResultsController = controller;
NSError* error = nil;
if (![controller performFetch:&error])
NSLog(@"error performing fetch: %@",error);
abort();
//Not sure what this does, seems redundant
//[self performFetch];
现在您必须通过您创建的 FRC 访问您的托管对象（不知道为什么需要self.searchResults）。
正如我所说，以最简单的形式实现：
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
// In the simplest, most efficient, case, reload the table view.
[self.tableView reloadData];
注意：您的删除代码应为： 这也是您的应用程序崩溃的原因，因为您在 FRC 能够报告上下文更改之前更新了表格。
- (void)tableView:(UITableView *)tableView
commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
forRowAtIndexPath:(NSIndexPath *)indexPath
if (editingStyle == UITableViewCellEditingStyleDelete)
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
[context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];
NSError *error = nil;
if (![context save:&error])
NSLog(@"Unresolved error %@", error);
abort();
【讨论】：
谢谢@Dan Shelly，您的提议使我的应用程序崩溃但出现其他错误。我正在使用部分和搜索栏... 什么是新的崩溃？您应该删除对表的任何“手动”更新，并使用 FRC 委托方法使用的更新。以上是关于删除部分的最后一行后，应用程序崩溃的主要内容，如果未能解决你的问题，请参考以下文章
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