UITableView dataSource必须从tableView:cellForRowAtIndexPath返回单元格

Question

我在我的搜索栏中添加了一个问题ViewController.

我收到以下错误:

Assertion failure in -[UISearchResultsTableView _configureCellForDisplay:forIndexPath:], /SourceCache/UIKit/UIKit-2935.137/UITableView.m:6509
2014-04-03 18:08:24.355 MyFood[6405:60b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:'

configureCell:

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath {        
    //    ToDos *toDo = [self.fetchedResultsController objectAtIndexPath:indexPath];
    if (viewMode==AlphabeticalOrder) {
        Inventory *toDo=nil;
        if (self.searchDisplayController.isActive) {
            toDo = [searchResults objectAtIndex:indexPath.row];
        } else {
            toDo=[inventoryProducts objectAtIndex:indexPath.row];
        }
        cell.textLabel.text = toDo.inventoryProductName;
        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        [formatter setDateStyle:NSDateFormatterShortStyle];
        NSDate *dt = toDo.expireDate;
        NSString *dateAsString = [formatter stringFromDate:dt];
        cell.detailTextLabel.text = [NSString stringWithFormat:@"Until: %@", dateAsString];
    } else {
        Inventory *toDo=nil;
        if (self.searchDisplayController.isActive) {
            NSDictionary *sectionDict=[searchResults objectAtIndex:indexPath.section];
            NSArray *sectionData=[sectionDict objectForKey:@"SECTION_DATA"];
            toDo = [sectionData objectAtIndex:indexPath.row];
        } else {
            NSDictionary *sectionDict=[inventoryProducts objectAtIndex:indexPath.section];
            NSArray *sectionData=[sectionDict objectForKey:@"SECTION_DATA"];
            toDo=[sectionData objectAtIndex:indexPath.row];
        }
        cell.textLabel.text = toDo.inventoryProductName;
        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        [formatter setDateStyle:NSDateFormatterShortStyle];
        NSDate *dt = toDo.expireDate;
        NSString *dateAsString = [formatter stringFromDate:dt];
        cell.detailTextLabel.text = [NSString stringWithFormat:@"Until: %@", dateAsString];
    }
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    // Configure the cell.
    [self configureCell:cell atIndexPath:indexPath];
    return cell;

}

代码搜索栏:

   - (void)filterContentForSearchText:(NSString*)searchText scope:(NSString*)scope
    {
        if (searchText.length!=0) {
            if (viewMode==AlphabeticalOrder) {
                NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:@"name contains[c] %@", searchText];
                //            [searchResults removeAllObjects];
                //            [searchResults addObjectsFromArray:[inventoryProducts filteredArrayUsingPredicate:resultPredicate]];
                searchResults=[inventoryProducts filteredArrayUsingPredicate:resultPredicate];
            } else {
                //-section mode
                NSMutableArray *newDataArray=[NSMutableArray array];
                for (NSMutableDictionary *aSectionDict in inventoryProducts) {
                    NSArray *sectionData=(NSArray*)[aSectionDict objectForKey:@"SECTION_DATA"];
                    NSPredicate *resultPredicate = [NSPredicate predicateWithFormat:@"name contains[c] %@", searchText];
                    NSArray *filteredArray=[sectionData filteredArrayUsingPredicate:resultPredicate];
                    NSDictionary *sectionDataModified=[NSDictionary dictionaryWithObjectsAndKeys:filteredArray,@"SECTION_DATA",[aSectionDict objectForKey:@"SECTION_TITLE"],@"SECTION_TITLE", nil];
                    [newDataArray addObject:sectionDataModified];
                }
                searchResults=[NSArray arrayWithArray:newDataArray];
            }
        }
    }

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

        return YES;
    }

有人可以帮忙吗？

Answer 1

由于您添加了搜索栏,因此需要检查单元格是否为零:

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

 // This is added for a Search Bar - otherwise it will crash due to
//'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:'
if (!cell) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}

   // Configure the cell.
    [self configureCell:cell atIndexPath:indexPath];
    return cell;

}

Answer 2

当您使用UISearchDisplayController时,结果显示在单独的UITableView中,该视图使用原始视图控制器作为委托和数据源.由于UITableView未在故事板中设置(它是动态创建和加载的),因此无法访问原型单元格.我能够通过使用以下方式获得类似的示例:

UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];

我有点担心,因为你要求一个tableview创建在不同的表视图中使用的单元格.

似乎更好的方法是不将您的单元格创建为原型单元格,而是创建它们并从单独的nib文件加载它们.

您还应该阅读UISearchDisplayController的文档,因为还需要更新dataSource和委托协议的其他几个细节,以反映有多个表视图正在运行的事实.

Answer 3

这告诉您您的方法：cellForRowAtIndexPath正在返回一个为零的单元格。从而产生此错误。

这行在这里：UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

将为零，因为您从未将任何内容分配给单元格，也没有对其执行任何操作。