Everyone keep writing about deleting a section. Well, I can't seem to get one added.
Currently, I am trying like this (which fails with NSInternalInconsistencyException):
UITableView *tv = (UITableView *) self.tableView;
if ([tv numberOfSections] == 1)
{
[tv beginUpdates];
[tv insertSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationTop];
NSLog(#"Inserted.. Brace for impact.");
[tv endUpdates];
}
NSLog(#"Section count after update: %d", [tv numberOfSections]); // Never reached
If I am correct, inserting a section with index 0 should place it at the top, bumping all the other sections down, right? Well, if I write out the numberOfSections right after the insertSections, there appears to be no change in the number of sections.
Any ideas?
Johan
Yes, thanks to both of you.
After some juggling, I finally managed to get it working. It was a combination of both your suggestions. The new data was never inserted, but also I did not have to increase the row count for the first item inserted, but only the second.
Did you also update your data source? You can't just update the table view without also updating the underlying data.
You need to update the numberOfSectionsInTableView message of the UITableViewDataSource class.
Related
I'm trying to collapse and expand a UITableView section with the help of deleteRowsAtIndexPaths. Nothing seems to happen though and I can't figure out why.
NSMutableArray *tmpArray = [NSMutableArray array];
for (int i=1; i<numberOfRowsInSection; i++){
NSIndexPath *tmpIndexPath = [NSIndexPath indexPathForRow:i inSection:section];
[tmpArray addObject:tmpIndexPath];
}
[_tableView beginUpdates];
[_tableView deleteRowsAtIndexPaths: tmpArray withRowAnimation:UITableViewRowAnimationAutomatic];
[_tableView endUpdates];
I've read through a lot of related questions, but nothing I do seem to help.
Any idea of what I'm doing wrong here?
UPDATE
Seems like _tableview is null. I'm guessing that's the main reason nothing is happening. Just don't understand that, since tableview is an outlet and it's already filled with rows and sections.
How can a tableview that's filled with rows and sections be null?
deleteRowAtIndexPath:withAnimation: just tells your table how it should display the table. You need to remove this row from your actual data at the same time. Aka tableView:NumberOfRowsInSection: need to return the correct number of lines.
you might be reloading the table view with original data after calling deleteRowsAt... make sure to change update your tableView data source in order to cope with the deleted changes i.e change the number of rows per section in the method numberOfRowsInSection
I am trying to delete some rows from UITableView and here is my code...
[self.responsesTableView beginUpdates];
[self.responsesTableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:self.processingIndexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
[self. responsesTableView endUpdates];
noOfRsponses --;
if (self.segFrndEveryone.selectedSegmentIndex == 0) {
[self.arrFriendComments removeObjectAtIndex:self.processingIndexPath.row];
}else {
[self.arrAllComments removeObjectAtIndex:self.processingIndexPath.row];
}
where one of the two arrays is my datasource depnding on the segment selected.
I am getting the following error and not sure how to deal with this.
The number of rows contained in an existing section after the update
(9) must be equal to the number of rows contained in that section
before the update (9), plus or minus the number of rows inserted or
deleted from that section (0 inserted, 1 deleted) and plus or minus
the number of rows moved into or out of that section (0 moved in, 0
moved out).'
You should update your data source before making manual changes to the UITableView.
// update the data source for the table change
noOfRsponses--;
NSMutableArray *targetArray = (self.segFrndEveryone.selectedSegmentIndex == 0) ? self.arrFriendComments : self.arrAllComments;
[targetArray removeObjectAtIndex:self.processingIndexPath.row];
// update the table view itself
[[self responsesTableView] beginUpdates];
[[self responsesTableView] deleteRowsAtIndexPaths:[NSArray arrayWithObject:self.processingIndexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
[[self responsesTableView] endUpdates];
Are you calling the removeObjectAtIndex on the correct array? Based on the error message, you haven't actually removed an object from the datasource that the tableview is expecting you to have removed from. I'm guessing that maybe you are removing from the wrong array.
And one other thing to try: remove the object first and then do the deleteRowsAtIndexPath.
You should use methods for sections
- (void)deleteSections:(NSIndexSet *)sections withRowAnimation:(UITableViewRowAnimation)animation;
I have a table view with 100 cells. At first, it is empty. Then, I call:
[_tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationLeft];
As there was nothing in the table view, I need to create several cells. However, I was expecting the table view to ask for 10 (to fit the screen size) cells... not 100 !
It doesn't happen when I simply reload the table view without any animation:
[_tableView reloadData];
This issue makes the table reloading very slow: is there a way to make it ask for 10 cells only ?
Edit
Maybe I wasn't clear enough: At first, the table has no entry. Then, I add 100 entries in my data source, and ask the table to reload: there is no visible cell before the reload, so the reloadRowsAtIndexPaths solution won't work.
It sounds like you're inserting new rows in the table, rather than reloading, so why not use:
[_tableView insertRowsAtIndexPaths:... withRowAnimation:...];
You may need to insert the section first:
[_tableView insertSections:... withRowAnimation:..];
http://developer.apple.com/library/ios/ipad/#documentation/uikit/reference/UITableView_Class/Reference/Reference.html
If you only want to reload lets say 10 cells, the following code will work.
int cellsToReload = 10;
NSMutableArray *indexPaths = [NSMutableArray arrayWithCapacity:cellsToReload];
for(int x = 0; x < cellsToReload; x++) {
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:x inSection:0];
[indexPaths addObject:indexPath];
}
[self.theTableView reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationLeft];
In the above code when you reloaded all of the tableview, you were reloading the entire section and not just a few rows. I'm guessing your tableview only had one section.
NSArray *paths = [_tableView indexPathsForVisibleRows];
[_tableView reloadRowsAtIndexPaths:paths withRowAnimation:UITableViewRowAnimationLeft];
will do exactly what you need - reload only visible raws, neither more, nor less.
I found out that this issue occurs only on iOS 5.1 and below. No need to file a bug as it is corrected in iOS 6. Thank you for your answers anyway !
I've done many hours researching in stackoverflow/google and did studied several posts regards to similar problems. Yet none of them addressed the particular problem I have.
In a nutshell, I have a NSMutableArray of NSMutableDictionay(-ies). Each dictionary contains a NSMutableArray. When I delete the last item in the array, I'd like to remove the dictionary as well. In tableview words, I would like to delete the section when deleting the last row in that section.
I am sure the data source is consistent.
this post here: UITableView: deleting sections with animation suggests to remove the section directly if the row to be removed is the last row.
This works fine if the section is the last section in my root array.
The bug I found is that, if the section is not the last section, the section after it will take its place. When the system is drawing the deletion animation, it would throw an NSInternalInconsistencyException.
Say, I have section 0 and section 1, both with one row. When I remove indexPath (0,0), I detect section 0 should go instead because it has only one row, then I remove section 0 in commitEditingStyle
The exception is thrown because user deleted Row 0 in Section 0, so the resulting number of rows in Section 0 should change from 1 to 0. However, after the removal, old Section 1 becomes Section 0 now, and it will return number of rows in Section 0 is 1.
Is there any suggestions here? Or am I missing something very simple?
My code in commitEditingSytle:
[tableView beginUpdates];
[... remove the item from array of this dictionary...]
// if last row in section, remove the section
NSNumber *section = [NSNumber numberWithUnsignedInteger: indexPath.section];
if ([[FoodTypes subtypes:section] count] == 0)
{
[...remove the dictionary from root array...]
[tableView deleteSections: [NSIndexSet indexSetWithIndex: indexPath.section] withRowAnimation:YES];
}
else
{
// otherwise, remove the row only
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}
[tableView endUpdates];
If you want to delete an dictionary from your array which is its object as subscripted variable then you need this single line.
[yourObject removeObjectAtIndex:indexPath.section];
and then reload the table by this line
[yourTable reloadData];
now since your table depends on this data source then it automatically remove from the table.
Update
I have posted my solution to this problem as an answer below. It takes a different approach from my first revision.
Original Question
I previously asked a question on SO that I thought solved my issues:
How to deal with non-visible rows during row deletion. (UITableViews)
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).
Before I lose you because of the shear length of my post, let me state the problem clearly, and you can read as much as you require to provide an answer.
Problem:
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.
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).
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.
So with that, if you are still interested…
Method that handles removal of sections and rows:
- (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;
}
My guess:
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).
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.
Hopefully this makes sense, it is a little complicate to write this out.
(note this code worked before with a different number of rows/sections. this particular configuration seems to give it issues)
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];
}
}
I notice that you're deleting the sections from the table first, and then deleting rows.
I know there's a complicated discussion of batch insertion and deletion for UITableViews in the Table View Programming Guide, but it doesn't specifically cover this.
I think what's happening is that deleting the sections is causing the row deletions to refer to the wrong row.
i.e. you want to delete section #2 and row #1 from section #4... but after you've deleted section #2, the old section #4 is now the third section, so you when you delete with the old NSIndexPath of (4, 1) you're deleting some random different row that may not exist.
So I think the fix might be as simple as swapping those two lines of code, so you're deleting the rows first, then the sections.
So finally here is my solution to this issue.
This method can be applied to tables of any size, any number of sections (as far as I can tell)
As before I have modified Matt Gallagher's tableview Code which places cell-specific logic in a separate cell controller. However, you can easily adapt this method to a different model
I have added the following (relevant) ivars to Matt's code:
NSArray *allTableGroups; //always has a copy of every cell controller, even if filtered
NSArray *filteredTableGroups; //always has a copy of the filtered table groups
Matt's original ivar:
NSArray *allTableGroups
…always points to one of the above arrays.
This can probably be refactored and improved significantly, but I haven't had the need. Also, if you use Core Data, NSFetchedResultsController makes this easier.
Now on to the method (I am trying to comment as much as I can):
- (void)createFilteredTableGroups{
//Checking for the usual suspects. all which may through an exception
if(model==nil)
return;
if(tableGroups==nil)
return;
if([tableGroups count]==0)
return;
//lets make a new array to work with
NSMutableArray *newTableGroups = [[allTableGroups mutableCopy] autorelease];
//telling the table what we are about to do
[self.tableView beginUpdates];
//array to track cells for deletion animation
NSMutableArray *indexesToRemove = [NSMutableArray array];
//loop through each section
for(NSMutableArray *eachSection in tableGroups){
//keeping track of the indexes to delete for each section
NSMutableIndexSet *indexesForSection = [NSMutableIndexSet indexSet];
[indexesForSection removeAllIndexes];
//increment though cell indexes
int rowIndex = 0;
//loop through each cellController in the section
for(ScheduleCellController *eachCellController in eachSection){
//Ah ha! A little magic. the cell controller must know if it should be displayed.
//This you must calculate in your business logic
if(![eachCellController shouldDisplay]){
//add non-displayed cell indexes
[indexesForSection addIndex:rowIndex];
}
rowIndex++;
}
//adding each array of section indexes, EVEN if it is empty (no indexes to delete)
[indexesToRemove addObject:indexesForSection];
}
//Now we remove cell controllers in newTableGroups and cells from the table
//Also, each subarray of newTableGroups is mutable as well
if([indexesToRemove count]>0){
int sectionIndex = 0;
for(NSMutableIndexSet *eachSectionIndexes in indexesToRemove){
//Now you know why we stuck the indexes into individual arrays, easy array method
[[newTableGroups objectAtIndex:sectionIndex] removeObjectsAtIndexes:eachSectionIndexes];
//tracking which cell indexPaths to remove for each section
NSMutableArray *indexPathsToRemove = [NSMutableArray array];
int numberOfIndexes = [eachSectionIndexes count];
//create array of indexPaths to remove
NSUInteger index = [eachSectionIndexes firstIndex];
for(int i = 0; i< numberOfIndexes; i++){
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:index inSection:sectionIndex];
[indexPathsToRemove addObject:indexPath];
index = [eachSectionIndexes indexGreaterThanIndex:index];
}
//delete the rows for this section
[self.tableView deleteRowsAtIndexPaths:indexPathsToRemove withRowAnimation:UITableViewRowAnimationTop];
//next section please
sectionIndex++;
}
}
//now we figure out if we need to remove any sections
NSMutableIndexSet *sectionsToRemove = [NSMutableIndexSet indexSet];
[sectionsToRemove removeAllIndexes];
int sectionsIndex = 0;
for(NSArray *eachSection in newTableGroups){
//checking for empty sections
if([eachSection count]==0)
[sectionsToRemove addIndex:sectionsIndex];
sectionsIndex++;
}
//updating the table groups
[newTableGroups removeObjectsAtIndexes:sectionsToRemove];
//removing the empty sections
[self.tableView deleteSections:sectionsToRemove withRowAnimation:UITableViewRowAnimationTop];
//updating filteredTableGroups to the newTableGroups we just created
self.filteredTableGroups = newTableGroups;
//pointing tableGroups at the filteredGroups
tableGroups = filteredTableGroups;
//invokes the animation
[self.tableView endUpdates];
}
I saw this same exact error as the result of prematurely releasing the background view of my custom tableview cell.
With NSZombieEnabled I got a an exception being thrown way down below an internal call to a function to prepare the cell for reuse. Without NSZombieEnabled, I was getting the Internal consistency error.
Incidentally when I fixed the retain/release issue on the background view of the cell, I was able to delete the last row of the section without having to delete the section explicitly.
Moral of the story: This error just means something bad is happening when you try to delete, and one of the things that happens when you delete is the cell gets prepared for reuse, so if you are doing anything custom with your tableview cells, look for a possible error there.
I suspect that you are forgetting to remove the object representing the section from your internal storage, so that the -numberOfSectionsInTableView: method is still returning 1 after all sections are deleted.
That's exactly what I was doing wrong when I had the same crash!
A much simpler way to address this is to update your data source, then call reloadSections
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationFade];
This will reload a single section. Alternatively you could use indexSetWithIndexesInRange: to reload multiple sections simultaneously.
or just do this
- (void)tableView:(UITableView *)tv
commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
forRowAtIndexPath:(NSIndexPath *)indexPath {
if(editingStyle == UITableViewCellEditingStyleDelete) {
//Delete the object from the table.
[directoriesOfFolder removeObjectAtIndex:indexPath.row];
[tv deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
}
}
directories of folder being your Array! Thats is all above codes didnt work for me! This is less expensive to do and just makes sense!