numberOfRowsInSection：核心數據和多個部分的方法

Question

我試圖顯示2個部分的表格視圖。第一部分將始終有1行，第二部分將具有與數據點一樣多的行。我使用的核心數據及以下的tableView：numberOfRowsInSection：方法...

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    if (section == 0) { 
     return 1; 
    } else { 
     id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section]; 
     return [sectionInfo numberOfObjects]; 
    } 
} 

不過，我收到以下錯誤：

Terminating app due to uncaught exception 'NSRangeException', reason: '* -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]'

任何幫助將不勝感激。謝謝。

NEW --------------------------------------------- ----------------------------------

這是目前實施的相關方法：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    if (section == 0) { 
     return 1; 
    } else { 
     NSUInteger frcSection = section - 1; 
     id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:frcSection]; 
     return [sectionInfo numberOfObjects]; 
    } 
} 

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{ 
    static NSString *CellIdentifier = @"Cell"; 
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 

    if (cell == nil) { 
     cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier]; 
    } 

    [self configureCell:cell atIndexPath:indexPath]; 
    return cell; 
} 

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath 
{ 
    if (indexPath.section == 0) { 
     cell.textLabel.text = entityOne.name; //entityOne object passed from previous VC 
    } else { 
     entityTwo = [self.fetchedResultsController objectAtIndexPath:indexPath]; 
     cell.textLabel.text = entityTwo.name; 
    } 
} 

- (void)controller:(NSFetchedResultsController *)controller 
    didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo 
      atIndex:(NSUInteger)sectionIndex 
    forChangeType:(NSFetchedResultsChangeType)type 
{ 
    NSUInteger frcSectionIndex = 0; 
    frcSectionIndex = sectionIndex + 1; 

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

     case NSFetchedResultsChangeDelete: 
      [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:frcSectionIndex] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 
    } 
} 

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

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

     case NSFetchedResultsChangeDelete: 
      [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 

     case NSFetchedResultsChangeUpdate: 
      [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath]; 
      break; 

     case NSFetchedResultsChangeMove: 
      [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      [tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 
    } 
} 

Answer 1

的原因是，所提取的結果控制器（FRC）僅具有一個部分（部＃0），要顯示在表視圖的第二部分（部＃1）。

這是可能的，但您必須在FRC節號和表格視圖節號之間進行映射，例如，

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{ 
    if (section == 0) { 
     return 1; 
    } else { 
     NSUInteger frcSection = section - 1; 
     id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:frcSection]; 
     return [sectionInfo numberOfObjects]; 
    } 
} 

cellForRowAtIndexPath需要相同的映射。

在FRC委託方法didChangeObject，didChangeSection您對調用表視圖方法（例如insertRowsAtIndexPaths）之前加1到節號。

---

新增：configureCell應該是這樣的：

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath 
{ 
    if (indexPath.section == 0) { 
     cell.textLabel.text = entityOne.name; //entityOne object passed from previous VC 
    } else { 
     NSIndexPath *frcIndexPath = [NSIndexPath indexPathForRow:indexPath.row inSection:(indexPath.section - 1)]; 
     entityTwo = [self.fetchedResultsController objectAtIndexPath:frcIndexPath]; 
     cell.textLabel.text = entityTwo.name; 
    } 
} 

和didChangeObject這樣的：

- (void)controller:(NSFetchedResultsController *)controller 
    didChangeObject:(id)anObject 
     atIndexPath:(NSIndexPath *)indexPath 
    forChangeType:(NSFetchedResultsChangeType)type 
     newIndexPath:(NSIndexPath *)newIndexPath 
{ 
    UITableView *tableView = self.tableView; 
    NSIndexPath *tvIndexPath = [NSIndexPath indexPathForRow:indexPath.row inSection:(indexPath.section + 1)]; 
    NSIndexPath *tvNewIndexPath = [NSIndexPath indexPathForRow:newIndexPath.row inSection:(newIndexPath.section + 1)]; 

    switch(type) { 
     case NSFetchedResultsChangeInsert: 
      [tableView insertRowsAtIndexPaths:@[tvNewIndexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 

     case NSFetchedResultsChangeDelete: 
      [tableView deleteRowsAtIndexPaths:@[tvIndexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 

     case NSFetchedResultsChangeUpdate: 
      [self configureCell:[tableView cellForRowAtIndexPath:tvIndexPath] atIndexPath:tvIndexPath]; 
      break; 

     case NSFetchedResultsChangeMove: 
      [tableView deleteRowsAtIndexPaths:@[tvIndexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      [tableView insertRowsAtIndexPaths:@[tvNewIndexPath] withRowAnimation:UITableViewRowAnimationFade]; 
      break; 
    } 
} 

你可能得到的想法：

• 從FRC索引路徑轉到表視圖索引路徑時，將一個添加到該節。
• 從表視圖索引路徑到FRC索引路徑時，從該部分中減去1。