我正在使用NSFetchedResultsController.以前我有一个类似的问题,当数据库没有tableview的条目,但后来创建一个,我发现必须至少有一个部分,所以我修复了.但是现在它崩溃了,例如我有两个部分,每个部分有一行,我删除了一行,所以部分应该不见了 – >崩溃.它表示更新前的部分数(2)不等于删除的数量(0).
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return 1 if the fetchedResultsController section count is zero
return [[fetchedResultsController sections] count] ? : 1;
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
// check if we really have any sections in the managed object:
if (!fetchedResultsController.sections.count) return @"Persoonlijk";
id <NSFetchedResultsSectionInfo> sectionInfo = [[fetchedResultsController sections] objectAtIndex:section];
return [sectionInfo name];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// check if we really have any sections in the managed object:
if (!fetchedResultsController.sections.count) return 0;
id <NSFetchedResultsSectionInfo> sectionInfo = [[fetchedResultsController sections] objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete schedule
NSManagedObjectContext *context = [fetchedResultsController managedObjectContext];
[context deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]];
// Save the context.
NSError *error = nil;
if (![context save:&error]) {
NSLog(@"Unresolved error %@,%@",error,[error userInfo]);
exit(-1);
}
}
}
解决方法
我找到了问题/解决方案：
对于这种情况,我没有必需的didChangeSection委托方法！
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {
NSLog(@"didChangeSection");
switch(type) {
case NSFetchedResultsChangeInsert:
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}