UITableView：用动画删除节 [英] UITableView: deleting sections with animation
问题描述
更新
我已将此问题的解决方案发布为以下答案。
I have posted my solution to this problem as an answer below. It takes a different approach from my first revision.
原始问题
先前提出了一个问题，我认为我解决了我的问题：
Original Question I previously asked a question on SO that I thought solved my issues:
如何在删除行期间处理不可见行。 （UITableViews）
但是，从UITableView中删除节时，我现在又遇到了类似的问题。
（当我改变表中的部分/行数时，它们重新出现）。
However, I now have similar problems again when removing sections from a UITableView. (they resurfaced when I varied the number of sections/rows in the table).
在我失去你之前，
问题：
如果从UITableView批量删除行和节，应用程序有时会崩溃。它取决于表的配置以及我选择删除的行和节的组合。
If batch deleting rows AND sections from a UITableView, the application crashes, sometimes. It depends on the configuration of the table and the combination of rows and sections I choose to remove.
日志说我崩溃了，因为它说我没有更新数据源和表格：
The log says I crashed because it says I have not updated the datasource and the table properly:
Invalid update: invalid number of rows in section 5. The number of rows contained in an existing section after the update (2) 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, 0 deleted).
现在很快，在写明确答案之前，我向你保证，和正确地从dataSource的部分。
Now quickly, before you write the obvious answer, I assure you I have indeed added and deleted the rows and sections properly from the dataSource. The explanation is lengthy, but you will find it below, following the method.
因此，如果你仍然感兴趣...
So with that, if you are still interested…
处理删除部分和行的方法：
- (void)createFilteredTableGroups{
//index set to hold sections to remove for deletion animation
NSMutableIndexSet *sectionsToDelete = [NSMutableIndexSet indexSet];
[sectionsToDelete removeIndex:0];
//array to track cells for deletion animation
NSMutableArray *cellsToDelete = [NSMutableArray array];
//array to track controllers to delete from presentation model
NSMutableArray *controllersToDelete = [NSMutableArray array];
//for each section
for(NSUInteger i=0; i<[tableGroups count];i++){
NSMutableArray *section = [tableGroups objectAtIndex:i];
//controllers to remove
NSMutableIndexSet *controllersToDeleteInCurrentSection = [NSMutableIndexSet indexSet];
[controllersToDeleteInCurrentSection removeIndex:0];
NSUInteger indexOfController = 0;
//for each cell controller
for(ScheduleCellController *cellController in section){
//bool indicating whether the cell controller's cell should be removed
NSString *shouldDisplayString = (NSString*)[[cellController model] objectForKey:@"filteredDataSet"];
BOOL shouldDisplay = [shouldDisplayString boolValue];
//if it should be removed
if(!shouldDisplay){
NSIndexPath *cellPath = [self indexPathOfCellWithCellController:cellController];
//if cell is on screen, mark for animated deletion
if(cellPath!=nil)
[cellsToDelete addObject:cellPath];
//marking controller for deleting from presentation model
[controllersToDeleteInCurrentSection addIndex:indexOfController];
}
indexOfController++;
}
//if removing all items in section, add section to removed in animation
if([controllersToDeleteInCurrentSection count]==[section count])
[sectionsToDelete addIndex:i];
[controllersToDelete addObject:controllersToDeleteInCurrentSection];
}
//copy the unfiltered data so we can remove the data that we want to filter out
NSMutableArray *newHeaders = [tableHeaders mutableCopy];
NSMutableArray *newTableGroups = [[allTableGroups mutableCopy] autorelease];
//removing controllers
int i = 0;
for(NSMutableArray *section in newTableGroups){
NSIndexSet *indexesToDelete = [controllersToDelete objectAtIndex:i];
[section removeObjectsAtIndexes:indexesToDelete];
i++;
}
//removing empty sections and cooresponding headers
[newHeaders removeObjectsAtIndexes:sectionsToDelete];
[newTableGroups removeObjectsAtIndexes:sectionsToDelete];
//update headers
[tableHeaders release];
tableHeaders = newHeaders;
//storing filtered table groups
self.filteredTableGroups = newTableGroups;
//filtering animation and presentation model update
[self.tableView beginUpdates];
tableGroups = self.filteredTableGroups;
[self.tableView deleteSections:sectionsToDelete withRowAnimation:UITableViewRowAnimationTop];
[self.tableView deleteRowsAtIndexPaths:cellsToDelete withRowAnimation:UITableViewRowAnimationTop];
[self.tableView endUpdates];
//marking table as filtered
self.tableIsFiltered = YES;
}
我的猜测：
问题似乎是：如果你看上面列出每个部分的单元格数，你会看到第5节似乎增加1.但是，这不是真的。原来的第5部分实际上已被删除，而另一部分已经取代了它（具体来说，它是旧的第10部分）。
The problem seems to be this: If you look above where I list the number of cells in each section, you will see that section 5 appears to increase by 1. However, this is not true. The original section 5 has actually been deleted and another section has taken its place (specifically, it is old section 10).
那么为什么表视图似乎没有实现这个？它应该知道我删除了旧部分和不应该期望现在位于旧部分的索引的新部分被删除部分的行数绑定。
So why does the table view seem not to realize this? It should KNOW that I removed the old section and should not expect a new section that is now located at the old section's index to be bound by the deleted section's number of rows.
希望这是有道理的，这是有点复杂的写出来。
Hopefully this makes sense, it is a little complicate to write this out.
（注意这个代码之前用不同的行数/ sections。这个特定的配置似乎给它的问题）
(note this code worked before with a different number of rows/sections. this particular configuration seems to give it issues)
推荐答案
您正在尝试从一个部分删除所有行，然后，此外，现在空部分。但是，足够（和适当）只删除该部分。其中的所有行也将被删除。下面是我项目中处理删除一行的一些示例代码。它需要确定是否应该从某个部分中只删除此行，或者删除整个部分，如果它是该部分中最后一行：
I’ve run into this problem before. You are trying to delete all rows from a section and then, in addition, that now empty section. However, it is sufficient (and proper) to remove that section only. All rows within it will be removed as well. Here is some sample code from my project that handles deletion of one row. It needs to determine whether it should remove only this row from a section or delete the entire section if it is the last remaining row in that section:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete)
{
// modelForSection is a custom model object that holds items for this section.
[modelForSection removeItem:[self itemForRowAtIndexPath:indexPath]];
[tableView beginUpdates];
// Either delete some rows within a section (leaving at least one) or the entire section.
if ([modelForSection.items count] > 0)
{
// Section is not yet empty, so delete only the current row.
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
}
else
{
// Section is now completely empty, so delete the entire section.
[tableView deleteSections:[NSIndexSet indexSetWithIndex:indexPath.section]
withRowAnimation:UITableViewRowAnimationFade];
}
[tableView endUpdates];
}
}
这篇关于UITableView：用动画删除节的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
