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当尝试从笔尖加载自定义 UITableViewCell 时，只有在主情节提要的原型单元格上设置了重用标识符时，我才能让单元格出现。如果设置为空白，我会收到来自 xcode 的警告，但代码运行正确。我在其他几个控制器中有类似的代码，但是这是唯一一个出现这个问题的控制器。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *cellIdentifier = @"AssetsTableCell";
AssetsTableCell *assetTableCell = (AssetsTableCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

int rightIndex = (indexPath.row * 4);
int rightMiddleIndex = (indexPath.row * 4) + 1;
int leftMiddleIndex = (indexPath.row * 4) + 2;
int leftIndex = (indexPath.row * 4) + 3;

if (assetTableCell == nil) {
    NSArray *topLevelObjects;
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) {
        topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"AssetsTableCell_iPhone" owner:nil options:nil];
        assetTableCell = (AssetsTableCell *)[topLevelObjects objectAtIndex:0];
        [assetTableCell setDelegate:self];

    }

    // Need to collect the badge details in groups of 4.    
    @try {
        NSArray *rowArray = [NSArray arrayWithObjects:[remoteContainers objectAtIndex:rightIndex], 
                                                      [remoteContainers objectAtIndex:rightMiddleIndex], 
                                                      [remoteContainers objectAtIndex:leftMiddleIndex],
                                                      [remoteContainers objectAtIndex:leftIndex], 
                                                      nil];

        NSDictionary *cellData = [NSDictionary dictionaryWithObjectsAndKeys:
                                  [rowArray objectAtIndex:0], @"LEFT_CONTAINER", 
                                  [rowArray objectAtIndex:1], @"LEFT_MIDDLE_CONTAINER", 
                                  [rowArray objectAtIndex:2], @"RIGHT_MIDDLE_CONTAINER", 
                                  [rowArray objectAtIndex:3], @"RIGHT_CONTAINER", nil];
        [assetTableCell populateCellData:cellData];
    }
    @catch (NSException *exception) {
        DLog(@"Exceeds boundary of remoteContainers array by %d.", ([remoteContainers count] % 4));
        int remainder = [remoteContainers count] % 4;

        switch (remainder) {
            case 1: {
                // Check to see the number of remaining containers left in the rest of the array. This dictates the way the final row must be constructed.
                if ([remoteContainers objectAtIndex:currentStartRangeIndex]) {
                    NSDictionary *cellData = [NSDictionary dictionaryWithObjectsAndKeys:[remoteContainers objectAtIndex:rightIndex], @"LEFT_CONTAINER", @"EMPTY_CELL", @"LEFT_MIDDLE_CONTAINER", @"EMPTY_CELL", @"RIGHT_MIDDLE_CONTAINER", @"EMPTY_CELL", @"RIGHT_CONTAINER", nil];
                    [assetTableCell populateCellData:cellData];                
                }                       
            }
                break;
            case 2: {
                // There are two elements at the end of the array.
                NSDictionary *cellData = [NSDictionary dictionaryWithObjectsAndKeys:[remoteContainers objectAtIndex:rightIndex], @"LEFT_CONTAINER", [remoteContainers objectAtIndex:rightMiddleIndex], @"LEFT_MIDDLE_CONTAINER", @"EMPTY_CELL", @"RIGHT_MIDDLE_CONTAINER", @"EMPTY_CELL", @"RIGHT_CONTAINER", nil];
                [assetTableCell populateCellData:cellData];
            }
                break;
            case 3: {
                // There are three elements at the end of the array.                    
                NSDictionary *cellData = [NSDictionary dictionaryWithObjectsAndKeys:[remoteContainers objectAtIndex:rightIndex], @"LEFT_CONTAINER", [remoteContainers objectAtIndex:rightMiddleIndex], @"LEFT_MIDDLE_CONTAINER", [remoteContainers objectAtIndex:leftMiddleIndex], @"RIGHT_MIDDLE_CONTAINER", @"EMPTY_CELL", @"RIGHT_CONTAINER", nil];
                [assetTableCell populateCellData:cellData];                    
            }
                break;
            default: {
                DLog(@"Thought the array had more elements, however was unable to determine the number of elements remaining in array.");

            }
                break;
        }
    }
}
return assetTableCell;

}

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1 回答 1

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看起来您仅在 tableView 无法为您出列单元格的情况下配置每个单元格。一方面，您的单元重用可能因此而中断。所以这是一个问题。

然后在情节提要的情况下，如果单元格标识符设置正确，那么 [tableview dequeueReusableCellWithIdentifier:] 将始终为您返回一个单元格。所以assetTableCell 不会是零，即使是第一次。

目前尚不清楚您的所有逻辑到底是什么，但您需要能够在assetTableCell 不为零的情况下正确设置单元格的内容。（要么是因为单元被回收，要么是因为单元来自情节提要缓存）

于 2011-12-13T23:41:21.227 回答