我正在处理消息应用以及我保存在核心数据中的所有消息。我使用NSFetchedResultsController和tableView在屏幕上显示它们。我的nsfetchedResultsController中的部分是一周的日子。我的意思是一个部分是例如今天另一部分例如是昨天。当我想添加应该插入新部分的新消息时，当我尝试将新对象插入到在tableview中生成新部分的核心数据时，我遇到了崩溃。这是我得到的日志：
无效更新：第0节中的行数无效。更新后的现有部分中包含的行数（12）必须等于更新前该部分中包含的行数（8），或者减去从该部分插入或删除的行数（插入1个，删除1个），加上或减去移入或移出该部分的行数（0移入，0移出）
此处是NSFETCHRESULTSCONTROLLER DELEGATE的代码
- (void)dataLoaderDidChangeContent:(GISingleConversationDataLoader *)controller {
[self.tableView endUpdates];
if (_shouldScrollToBottomAfterUpdate) {
[self scrollToBottomAnimated:NO];
}
}
- (void)dataLoaderWillChangeContent:(GISingleConversationDataLoader *)controller {
[self.tableView beginUpdates];
}
- (void)dataLoader:(GISingleConversationDataLoader *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
if ([self.tableView numberOfSections]) {
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationBottom];
} else {
[tableView insertSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationNone];
}
_shouldScrollToBottomAfterUpdate = YES;
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationNone];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationNone];
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationNone];
break;
}
}
数据来源：
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [self.dataProvider.fetchedResultsController.sections count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if ([[self.dataProvider.fetchedResultsController sections] count] < 1) {
return 0;
}
id <NSFetchedResultsSectionInfo> sectionInfo = [[self.dataProvider.fetchedResultsController sections] objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
GICDChatMessage *message = [self _messageAtIndexPath:indexPath];
GIChatMessageType type = [message.type integerValue];
NSString *kMessageTypeKey = [message isOutgoing] ? kOutgoingMessageKey : kIncomingMessageKey;
NSString *CellIdentifier; CellIdentifier = self.cellIdentifiers[@(type)][kMessageTypeKey];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
self.configureCellBlock(cell, message, indexPath);
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
[cell setBackgroundColor:tableView.backgroundColor];
return cell;
}
我创建NSFetchedResultsController并在数据加载器中管理他。我创建它以使我的viewController更轻。
这是我的数据加载器实现：
- (id)initWithConversation:(GIConversation *)conversation delegate:(id<GISingleConversationDataLoaderProtocol>)delegate {
self = [super init];
if (self) {
_conversation = conversation;
_delegate = delegate;
[self resultsController];
[_fetchedResultsController setDelegate:self];
[self performFetch];
}
return self;
}
- (NSPredicate *)predicate {
return [NSPredicate predicateWithFormat:@"conversationJid == %@", _conversation.jid];
}
- (NSString *)entityName {
return @"GICDChatMessage";
}
- (NSArray *)sortDescriptors {
return @[[NSSortDescriptor sortDescriptorWithKey:@"receivedAt" ascending:YES]];
}
- (NSFetchedResultsController*)resultsController {
if (_fetchedResultsController == nil) {
_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:[self fetchRequest] managedObjectContext:[self context] sectionNameKeyPath:@"sectionNameKeyPath" cacheName:nil];
}
return _fetchedResultsController;
}
-(void)performFetch {
if (_fetchedResultsController) {
[_fetchedResultsController performFetch:nil];
[_delegate dataLoaderDidChangeContent:self];
}
}
- (NSFetchRequest*)fetchRequest {
NSFetchRequest *result = [NSFetchRequest fetchRequestWithEntityName:[self entityName]];
NSPredicate *mainPredicate = [self predicate];
result.predicate = mainPredicate;
result.sortDescriptors = [self sortDescriptors];
return result;
}
- (NSManagedObjectContext *)context {
return [[GICoreDataManager sharedInstance] mainContext];
}
#pragma mark - fetch change
- (void)controller:(NSFetchedResultsController *)controller
didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath
forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath {
[_delegate dataLoader:self
didChangeObject:anObject
atIndexPath:indexPath
forChangeType:type
newIndexPath:newIndexPath];
}
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
[_delegate dataLoaderWillChangeContent:self];
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[_delegate dataLoaderDidChangeContent:self];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
[_delegate dataLoader:self didChangeSection:sectionInfo atIndex:sectionIndex forChangeType:type];
}
> sectionNameKeyPath是一个在我的模型类类别中定义的键，它看起来是：
- (NSString *)sectionNameKeyPath {
NSTimeInterval timeInterval = [self.receivedAt timeIntervalSinceNow];
NSString *string = [[GICDChatMessage timeIntervalFormatter] stringForTimeInterval:roundf(timeInterval / oneDayTimeInterval) * oneDayTimeInterval];
if ([string isEqualToString:NSLocalizedString(@"just now", nil)]) {
string = NSLocalizedString(@"Today", nil);
}
return string;
}
它只是为每天的消息排序。
你知道是什么导致了这个问题或者我做错了什么吗？
我的英语不好，所以如果你不明白我的意思，请问我，我会尝试更清楚地解释。
答案 0 :(得分：3)
您需要实现didChangeSection：
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
switch(type) {
case NSFetchedResultsChangeInsert:
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex]
withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]
withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
编辑您还需要删除管理部分的代码部分：
if ([self.tableView numberOfSections]) {
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationBottom];
} else {
[tableView insertSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationNone];
}
答案 1 :(得分：0)
您尚未实施NSFetchedResultsControllerDelegate协议的任何方法。相反，您已经编写了具有相似名称的自定义方法。例如，这里介绍了您发布的方法：
- (void)dataLoaderWillChangeContent:(GISingleConversationDataLoader *)controller {
[self.tableView beginUpdates];
}
虽然上述方法的名称与NSFetchedResultsControllerDelegate协议的方法类似，但它不是同一种方法，因此永远不会被提取的结果控制器调用。如果您希望获取的结果控制器调用它，那么您需要实现该方法的声明：
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller;
同样，您应该更改代码的该部分中其他方法的名称和签名，以匹配Core Data提供的实际API。
答案 2 :(得分：0)
汇总更新
然后在controllerDidChangeContent中，您需要处理所有收到的更新并转发到UITableView
此代码非常适合我：
class SomeVC: UITableViewController {
/* ... */
// Add properties for each expected update type
var insertedSectionIndexes = NSMutableIndexSet()
var deletedSectionIndexes = NSMutableIndexSet()
var deletedRowIndexPaths: Set<NSIndexPath> = []
var insertedRowIndexPaths: Set<NSIndexPath> = []
var updatedRowIndexPaths: Set<NSIndexPath> = []
}
extension SomeVC: NSFetchedResultsControllerDelegate {
func controllerWillChangeContent (controller: NSFetchedResultsController) {}
func controller(controller: NSFetchedResultsController,
didChangeObject anObject: NSManagedObject,
atIndexPath indexPath: NSIndexPath?,
forChangeType type: NSFetchedResultsChangeType,
newIndexPath: NSIndexPath?) {
switch type {
case .Insert: insertedRowIndexPaths.insert(indexPath!)
case .Update: updatedRowIndexPaths.insert(indexPath!)
case .Move:
if newIndexPath?.section != indexPath?.section {
insertedRowIndexPaths.insert(newIndexPath!)
deletedRowIndexPaths.insert(indexPath!)
}
case .Delete: deletedRowIndexPaths.insert(indexPath!)
}
}
func controller(controller: NSFetchedResultsController,
didChangeSection sectionInfo: NSFetchedResultsSectionInfo,
atIndex sectionIndex: Int,
forChangeType type: NSFetchedResultsChangeType) {
switch type {
case .Insert: insertedSectionIndexes.addIndex(sectionIndex)
case .Delete: deletedSectionIndexes.addIndex(sectionIndex)
default:()
}
}
func controllerDidChangeContent (controller: NSFetchedResultsController) {
tableView?.beginUpdates()
tableView?.deleteSections(deletedSectionIndexes, withRowAnimation: .None)
tableView?.insertSections(insertedSectionIndexes, withRowAnimation: .None)
updatedRowIndexPaths.subtractInPlace(deletedRowIndexPaths)
updatedRowIndexPaths.subtractInPlace(insertedRowIndexPaths)
tableView?.deleteRowsAtIndexPaths(Array(deletedRowIndexPaths), withRowAnimation: .Automatic)
tableView?.insertRowsAtIndexPaths(Array(insertedRowIndexPaths), withRowAnimation: .Automatic)
tableView?.reloadRowsAtIndexPaths(Array(updatedRowIndexPaths), withRowAnimation: .Automatic)
tableView?.endUpdates()
// Do not forget to clean up!
insertedSectionIndexes.removeAllIndexes()
deletedSectionIndexes.removeAllIndexes()
deletedRowIndexPaths = []
insertedRowIndexPaths = []
updatedRowIndexPaths = []
}
}
注意：来自Xcode 7 beta 2的代码，某些方法可能被称为不同