Question

每当我在UITableView中有数据并且我开始删除时，它都可以正常工作。但是，当我到达表中的最后一个对象并删除它时，它会崩溃。

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (1), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted).'

以下是我正在编辑的内容：

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        if ([myData count] >= 1) {
            [tableView beginUpdates];
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            [myData removeObjectAtIndex:[indexPath row]];

            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentsDirectory = [paths objectAtIndex:0];
            NSString *somepath = [documentsDirectory stringByAppendingPathComponent:@"something.plist"];
            [myData writeToFile:somepath atomically:YES];
            [table reloadData];
            if ([myData count] == 0) {
                [tableView endUpdates];
                [tableView reloadData];
            }
            else {
            [tableView endUpdates];
            }
        }
    }   
}

还有这个：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    if ([myData count] != 0) {
        return [myData count];
    }
    else {
        return 1;
    }
}

我返回1的原因是因为我在cellForRowAtIndexPath创建了一个“无数据保存”的单元格。这就是我的意思：

-(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] autorelease];
    }    
    if ([cityData count] != 0) {
        //normal setup removed for clarity
    }
    else {
        cell.textLabel.text = @"No saved data!";
    cell.textLabel.font = [UIFont boldSystemFontOfSize:14]; 
    cell.textLabel.textAlignment = UITextAlignmentCenter;
    cell.selectionStyle = UITableViewCellSelectionStyleNone;
        cell.tag = 1;
    return cell;
    }
}

那么，我在编辑代码中出错是为了得到这个错误？谢谢！

Answer 1

如果删除表中的最后一行，UITableView代码预计剩余0行。它会调用您的UITableViewDataSource方法来确定剩余的数量。由于您有一个“无数据”单元格，它返回1，而不是0.因此，当您删除表格中的最后一行时，请尝试调用-insertRowsAtIndexPaths:withRowAnimation:以插入“无数据”行。此外，您不应该在此方法中的任何位置调用-reloadData。 -endUpdates将负责重新加载受影响的行。试试这个：

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        if ([myData count] >= 1) {
            [tableView beginUpdates];
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            [myData removeObjectAtIndex:[indexPath row]];

            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *documentsDirectory = [paths objectAtIndex:0];
            NSString *somepath = [documentsDirectory stringByAppendingPathComponent:@"something.plist"];
            [myData writeToFile:somepath atomically:YES];

            if ([myData count] == 0) {
                [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            }
            [tableView endUpdates];
        }
    }   
}

Answer 2

首先从myData中删除，然后从tableview中删除。

-(void)tableView:(UITableView *)tableView commitEditingStyle: 
(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

if (editingStyle == UITableViewCellEditingStyleDelete) {
        //somehting...
        [myData removeObjectAtIndex:[indexPath row]];
        [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        //somehting...
    }
}

}

Answer 3

方法tableView:numberOfRowsInSection必须始终返回确切的行数：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    return [myData count];
}

删除最后一行后，您可能想要删除整个部分。只需在deleteSections:withRowAnimation:和beginUpdates块中调用endUpdated;

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        [tableView beginUpdates];
        [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        [myData removeObjectAtIndex:[indexPath row]];
        NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *somepath = [documentsDirectory stringByAppendingPathComponent:@"something.plist"];
        [myData writeToFile:somepath atomically:YES];
        if ([myData count] == 0) {
            // NEW! DELETE SECTION IF NO MORE ROWS!
            [tableView deleteSections:[NSIndexSet indexSetWithIndex:[indexPath section]] withRowAnimation:UITableViewRowAnimationFade];
        }
        [tableView endUpdates];
    }   
}

NSInternalInconsistencyException（无效行数）

3 个答案: