如何使用动画从UITableView删除行? [英] How to delete rows from UITableView with animation?

问题描述

我在从表视图中删除行时遇到问题.当按下该行中的删除按钮时，我正在使用以下代码:

I am having problems with deleting rows from table view. I am using the code below when the delete button in the row was pressed:

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:control.tag-100 inSection:0];
[resultList removeObjectAtIndex:indexPath.row];
[resultView beginUpdates];
[resultView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
[resultView endUpdates];
//[resultView reloadData];

第一行已成功删除，但随后索引不正确.因此，当我删除最后一行时，它会给出索引超出范围的异常.

First row was deleted successfully but then, indexes were not correct. So when I delete the last row, it gives index out of bounds exception.

单元格生成代码为:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"personalizeTableCell";

    PersonalizeCell *cell = (PersonalizeCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil)
        cell = [[PersonalizeCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];        
    cell.title.text = @"text";
    cell.rateView.tag = indexPath.row + 100;
    return cell;
}

我在哪里错了?

更新:

    for (NSInteger j = 0; j < [venuesTableView numberOfSections]; ++j)
    {
        for (NSInteger i = 0; i < [venuesTableView numberOfRowsInSection:j]; ++i)
        {
           PersonalizeCell* cell = (PersonalizeCell*)[venuesTableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:j]];
           cell.rateView.tag = 100 + i;
        }
    }

解决了我的问题.感谢Nenad M.

solved my problem. Thanks to Nenad M.

推荐答案

假设您的 [NSIndexPath indexPathForRow:control.tag-100 inSection:0]; 返回正确的索引路径....您是否尝试过将 removeObjectAtIndex 调用移至开始/结束更新括号"内?:

Assuming your [NSIndexPath indexPathForRow:control.tag-100 inSection:0]; returns the right index path.... Did you try moving the removeObjectAtIndex call inside the begin-/end-updates "bracket"?:

NSIndexPath *indexPath = [NSIndexPath indexPathForRow:control.tag-100 inSection:0];
[resultView beginUpdates];
[resultList removeObjectAtIndex:indexPath.row];
[resultView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
[resultView endUpdates];

更新:

显然，删除第一个单元格后，您的 cell.rateView.tag 错误.因此，在每次删除后(即每个 removeObjectAtIndex ... )，您都必须在剩余的tableview-cells上重复迭代，并重新分配适当的标记值( cell.rateView.tag = indexPath.row + 100 )！否则，您的 [NSIndexPath indexPathForRow:control.tag-100 inSection:0]; 将返回错误的indexPath，从而导致超出范围的错误！

UPDATE:

Obviously your cell.rateView.tag become wrong, after youe delete your first cell. So after every deletion (i.e. every removeObjectAtIndex...) you must re-iterate over your remaining tableview-cells an re-assign the proper tag-value (cell.rateView.tag = indexPath.row + 100)! Otherwise your [NSIndexPath indexPathForRow:control.tag-100 inSection:0]; will return a wrong indexPath, therefore leading to your out of bounds error!

您不必重新加载整个表，只需循环遍历其余单元格，然后在 [resultView endUpdates]; :

You don't have to reload the entire table, just loop through the remaining cells an re-assign the tag-value after [resultView endUpdates];:

NSMutableArray *cells = [[NSMutableArray alloc] init];
for (NSInteger j = 0; j < [tableView numberOfSections]; ++j)
{
    for (NSInteger i = 0; i < [tableView numberOfRowsInSection:j]; ++i)
    {
        [cells addObject:[tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:j]]];
    }
}

现在做:

for (PersonalizeCell* cell in cells)
{
    cell.rateView.tag = // new calculated tag
}

(或者甚至直接在第一个代码段的内部循环中进行重新分配.)

(Or do the re-assignment even in the inner-loop of the first code-snippet directly.)

下面是整个过程的一些非常典型的代码，示例中的表格两行:

Here's some really typical code for the whole process, two lines from the table in the example:

请注意，facebookRowsExpanded是您必须具有的类变量:

Note that facebookRowsExpanded is a class variable you must have:

if ( [theCommand isEqualToString:@"fbexpander"] )
{
NSLog(@"expander button......");
[tableView deselectRowAtIndexPath:indexPath animated:NO];

NSArray *deleteIndexPaths;
NSArray *insertIndexPaths;

facebookRowsExpanded = !facebookRowsExpanded;
// you must do that BEFORE, not AFTER the animation:

if ( !facebookRowsExpanded ) // ie, it was just true, is now false
    {
    deleteIndexPaths = [NSArray arrayWithObjects:
            [NSIndexPath indexPathForRow:2 inSection:0],
            [NSIndexPath indexPathForRow:3 inSection:0],
             nil];
    [tableView beginUpdates];
    [tableView
        deleteRowsAtIndexPaths:deleteIndexPaths
        withRowAnimation: UITableViewRowAnimationMiddle];
    [tableView endUpdates];
    }
else
    {
    insertIndexPaths = [NSArray arrayWithObjects:
            [NSIndexPath indexPathForRow:2 inSection:0],
            [NSIndexPath indexPathForRow:3 inSection:0],
             nil];
    [tableView beginUpdates];
    [tableView
        insertRowsAtIndexPaths:insertIndexPaths
        withRowAnimation: UITableViewRowAnimationMiddle];
    [tableView endUpdates];
    }

// DO NOT do this at the end: [_superTableView reloadData];
return;
}

注意:您的 numberOfRowsInSection 代码必须使用facebookRowsExpanded

NOTE: your code for numberOfRowsInSection must use facebookRowsExpanded

(类似于如果facebookRowsExpanded返回7，否则返回5")

(it will be something like "if facebookRowsExpanded return 7, else return 5")

注意: cellForRowAtIndexPath 的代码必须使用facebookRowsExpanded.

NOTE: your code for cellForRowAtIndexPath must use facebookRowsExpanded.

(它必须返回正确的行，具体取决于您是否展开.)

(it has to return the correct row, depending on whether or not you are expanded.)

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