This is the first time I ask a question here, but I have to say this site has been a tremendous help for me over the last couple months (iphone-dev-wise), and I thank you for that.
However, I didn't find any solution for this problem I'm having:
I have a UITableView with 2 sections, and no rows when the app is launched for the first time. The user can fill the sections later on as he wishes (the content is not relevant here). The UITableView looks good when filled with rows, but looks pretty ugly when there is none (the 2 header sections are stuck together with no white space in between). That is why I'd like to add a nice "No row" view in between when there is no row.
I used viewForFooterInSection:
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
if(section == 0)
{
if([firstSectionArray count] == 0)
return 44;
else
return 0;
}
return 0;
}
- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section{
if(section == 0)
{
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(200, 10, 50, 44)];
label.backgroundColor = [UIColor clearColor];
label.textColor = [UIColor colorWithWhite:0.6 alpha:1.0];
label.textAlignment = UITextAlignmentCenter;
label.lineBreakMode = UILineBreakModeWordWrap;
label.numberOfLines = 0;
label.text = #"No row";
return [label autorelease];
}
return nil;
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 2;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
if(section == 0)
{
return [firstSectionArray count];
}
return [secondSectionArray count];
}
This works great : the footer view appears only when there is no row in section 0.
But my app crashes when I enter edit mode and delete the last row in section 0:
Assertion failure in -[UIViewAnimation initWithView:indexPath:endRect:endAlpha:startFraction:endFraction:curve:animateFromCurrentPosition:shouldDeleteAfterAnimation:editing:]
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Cell animation stop fraction must be greater than start fraction'
This does not happen when there are several rows in section 0. It only happens when there is only one row left.
Here's the code for edit mode:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
// If row is deleted, remove it from the list.
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Find the book at the deleted row, and remove from application delegate's array.
if(indexPath.section == 0)
{ [firstSectionArray removeObjectAtIndex:indexPath.row]; }
else
{ [secondSectionArray removeObjectAtIndex:indexPath.row]; }
// Animate the deletion from the table.
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationBottom];
[tableView reloadData];
}
}
Does anyone have any idea why this is happening?
Thanks
It looks like what it happening is that internally Apple's UITableView code is assuming that when you delete a row, the first section of your view will get shorter. By making the section header footer suddenly get taller to compensate for the last row, you appear to be confusing it.
Two ideas for you to try:
1. try making the optional section footer a pixel or two smaller than the table cell that's going away, so that the animation code gets to do a pixel or two of animation
2. instead of deleting the only row of your table, when there are no "real" data rows let the table still have numberOfRowsInSection return 1 and make a fake "no data" cell rather than using a table footer for the "no data" case.
This is one of those cases where you just have to accept that Apple has written half of your program for you and you have to conform to some choices your co-author has made, whether you like them or not.
make empty section
use table header in this section instead of footer in first section
- (UIView *) tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section {
if (section != OTHER_SECTION_INDEX) {
return nil;
}
//your code here
}
- (CGFloat) tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
if (section != OTHER_SECTION_INDEX) {
return 0;
}
//your code
}
it shouldn't be necessary to call both deleteRowsAtIndexPaths:withAnimation: and reloadData on tableView.
the problem you are seeing is the problem i see manifesting in the call to deleteRowsAtIndexPaths:withAnimation:, and thus for you, it's never getting to reloadData anyway.
a simpler solution to having to create new cells, manage them, deal with all of the places where a different cell has to be dealt with, is to use reloadSections:withAnimation: when dealing with a section that is going from 0 to 1 row or 1 to 0 rows.
i.e. replace the following lines of code:
if(indexPath.section == 0)
{ [firstSectionArray removeObjectAtIndex:indexPath.row]; }
else
{ [secondSectionArray removeObjectAtIndex:indexPath.row]; }
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationBottom];
with the following
BOOL useReloadSection;
if (indexPath.section == 0)
{
[firstSectionArray removeObjectAtIndex:indexPath.row];
useReloadSection = 0 == firstSectionArray.count;
}
else
{
[secondSectionArray removeObjectAtIndex:indexPath.row];
useReloadSection = 0 == secondSectionArray.count;
}
if (useReloadSection)
[tableView reloadSections:[NSIndexSet indexSetWithIndex:indexPath.section]
withRowAnimation:UITableViewRowAnimationBottom];
else
[tableView deleteRowsAtIndexPaths:#[indexPath]
withRowAnimation:UITableViewRowAnimationBottom];
I was experiencing the same crash, looks like it's a bug in the OS.
My specific use case pertains to a UITableView with collapsable / expandable sections. I need section dividers (this is what I was using the section footer for) but not row dividers (can't simply use the cell separator).
I wasn't able to resolve the issue by adjusting the height of the section footer. But switching to using a section header did the trick, the bug/crash is no longer occurring.
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
CGRect frame = (CGRect){0, 0, self.view.bounds.size.width, 1};
UIView *view = [[UIView alloc] initWithFrame:frame];
view.backgroundColor = [UIColor commentReplyBackground];
return view;
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
return 1.0f;
}
For those of you who still need the section footer, you can also try changing the TableView style to UITableViewStyleGrouped. This seems to bypass the issue. In order to get the same visual appearance, you just have to set all your other footers and headers to CGFLOAT_MIN.
Related
I don't want to show the "no results" text while my server is processing a search query.
I figured out the exact coordinates of the table cell that contains the label and attempted to cover it.
self.noResultsCoverView = [[[UIView alloc] initWithFrame:CGRectMake(
0.0,
44.0,
320.0,
43.0
)] autorelease];
self.noResultsCoverView.backgroundColor = [UIColor whiteColor];
[self.searchDisplayController.searchResultsTableView addSubview:self.noResultsCoverView];
To my chagrin, my cover was above the table view, but below the label. I need the cover to be above the label. searchResultsTableView::bringSubviewToFront didn't work, which makes me believe that the label isn't a child of the searchResultsTableView at all.
BTW, this Stack Overflow answer doesn't quite work for me. It works on the very first search, but flashes a weird black cover on subsequent searches.
this should do the work properly. The code to return at least one cell:
BOOL ivarNoResults; // put this somewhere in #interface or at top of #implementation
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
if (tableView == self.searchDisplayController.searchResultsTableView) {
if (filteredList.count == 0) {
ivarNoResults = YES;
return 1;
} else {
ivarNoResults = NO;
return [filteredList count];
}
}
// {…}
// return the unfiltered array count
}
and for "showing" the clean cell:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
if (tableView == self.searchDisplayController.searchResultsTableView && ivarNoResults) {
static NSString *cleanCellIdent = #"cleanCell";
UITableViewCell *ccell = [tableView dequeueReusableCellWithIdentifier:cleanCellIdent];
if (ccell == nil) {
ccell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cleanCellIdent] autorelease];
ccell.userInteractionEnabled = NO;
}
return ccell;
}
// {…}
}
The easiest way to work around this is to return 1 in numberOfRowsInSection while the query is in progress and leave the dummy cell empty or set its hidden property to YES so it is not visible.
Try this it worked for me
In the UISearchDisplayController delegate do this:=
- (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString
{
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, 0.001);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
for (UIView* v in self.searchDisplayController.searchResultsTableView.subviews) {
if ([v isKindOfClass: [UILabel class]] &&
[[(UILabel*)v text] isEqualToString:#"No Results"]) {
[(UILabel*)v setText:#""];
break;
}
}
});
return YES;
}
You need to realize that when you have a UISearchDisplayController, and the search bar is active, the UITableView argument passed into your UITableView data source and delegate methods is in fact NOT your tableView object, but a tableView managed by the UISearchDisplayController, intended to display "live" search results (perhaps results filtered from your main data source, for example).
You can easily detect this in code, and then return the appropriate result from the delegate/data source method, depending on which tableView object is asking.
For example:
- (NSInteger)tableView:(UITableView *)tv numberOfRowsInSection:(NSInteger)section
{
if (tv == self.searchDisplayController.searchResultsTableView) {
// return the number of rows in section for the visible search results.
// return a non-zero value to suppress "No results"
} else {
// return the number of rows in section for your main data source
}
}
The point is that your data source and delegate methods are serving two tables, and you can (and should) check for which table is asking for data or delegation.
By the way, the "No results" is (I believe) provided by a background image which the UISearchDisplayController displays when the delegate says there are no rows... You are not seeing a 2-row table, the first blank and the second with text "No results". At least, that's what I think is happening there.
I want to add row dynamically. I have tableview list of building names. If some one choose building(didSelectRowAtIndexPath) then respective floors of building should get added dynamically as subrow. Its like maximizing and minimizing the subrow on respective building list selection. How do I do this. Thanks in advance...
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
// There is only one section.
if (tableView == indoortable || tableView == indoortable_iPad)
{
return 1;
}
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
// Return the number of time zone names.
if (tableView == indoortable || tableView == indoortable_iPad)
{
return [indoorZones count];
}
}
cellForRowAtIndexPath method:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if (tableView == indoortable || tableView == indoortable_iPad)
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleGray; //cell bg
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
}
// Set up the cell.
//cell.textLabel.text = [copyListOfItems objectAtIndex:indexPath.row];
cell.textLabel.text =[indoorZones objectAtIndex: indexPath.row];
//[cell setIndentationLevel:[[self.indoorZones objectAtIndex:indexPath.row] intValue]];
return cell;
}
}
didSlectRowAtIndexPath method:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
zonesFloor = [[NSMutableArray alloc]init];
zonesFloorA = [[NSArray alloc] initWithObjects:#"Gr fl",#"1st fl",#"2nd fl",nil];
[zonesFloor addObject:zonesFloorA];
if (tableView == indoortable )
{
NSUInteger i=indexPath.row+1;
for (NSArray *count in self.indoorZones) //app is crashing here giving error.......Collection <__NSArrayM: 0x4b1d550> was mutated while being enumerated.
{
[zonesFloor addObject:[NSIndexPath indexPathForRow:i inSection:0]];
[self.indoorZones insertObject:zonesFloor atIndex:i++];
}
[[self indoortable] beginUpdates];
[[self indoortable] insertRowsAtIndexPaths:(NSArray *)zonesFloor withRowAnimation:UITableViewRowAnimationNone];
[[self indoortable] endUpdates];
}
if (tableView == indoortable_iPad )
{
//some logic
}
[tableView deselectRowAtIndexPath:selectedIndexPath animated:NO];
}
It Gives following error [__NSArrayI compare:]: Or [NSIndexPath _fastCStringContents:]: unrecognized selector sent to instance. I tried many ways but may be I am lacking somewhere. Please suggest. thanks in advance.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
//NSIndexPath *selectedIndexPath = [self.indoortable indexPathForSelectedRow];
zonesFloorA = [[NSArray alloc] initWithObjects:#"Gr fl",#"1st fl",#"2nd fl",nil];
if (tableView == indoortable )
{
for (NSString *str in zonesFloorA) {
[indoorZones addObject:str];
}
//[[self indoortable] beginUpdates];
//[[self indoortable] insertRowsAtIndexPaths:(NSArray *)zonesFloor withRowAnimation:UITableViewRowAnimationNone];
//[[self indoortable] endUpdates];
}
if (tableView == indoortable_iPad )
{
//some logic
}
[tableView reloadData];
}
may this meet your requirement
Okay, so not to sound mean, but there are almost too many issues here to count.
Let's start with a basic explanation of how tableView's work so that you can start to fix this:
First, the tableView asks how many sections are in the table by calling:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
}
In your code, you simply tell it that it has one section. However, in your later code, when you try to add rows to your table, you tell it that you want to add your rows to a second section (with an index of 1). Therefore, you either need to add these rows to section 0 instead, or update the above method to tell it that, sometimes, there are two sections.
Second, the tableView asks how many rows are in each section of the table by calling:
- (NSInteger)tableView:(UITableView *)tableView
numberOfRowsInSection:(NSInteger)section {
}
In your code, you are simply returning the number of zones. However, like above, you need to include the rows that you have added to your table. If you are adding them to a different section, then you need to return different values, depending on how many rows are in the section with the index asked for in the section variable. If they are all in the same section, then you need to add them up and return the correct value.
Third, the tableView asks for an actual cell for the row by calling:
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
}
In your code, you are only returning a cell which has data populated by the indoorZones array, but you also need to supply cells which are configured properly for the specific zone/floor. Again, you either need to determine this by section number or row number as appropriate.
Finally, when you click on a row, the tableview tells you by calling the following method:
- (void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
}
In this method, you need to update your data source that is used by the previous functions so that when they get called again, they will provide the correct data. Your data source must mirror the way that you want your table view to look. In your case, you have an array called indoorZones. This is good if you just want to display a list of zones, which is what you start off doing. However, when you want to add more rows, you need to add more rows to your data source first, so that when the tableView starts this process over, it is already there.
If you want everything to stay in one section, then I would come up with a data source that can include both types of rows, and be able to distinguish between them so that cellForRowAtIndexPath can create the proper type of cell and return it.
If you want two sections, then I would add a second array for the second section (since it is not the same type of data) and return the appropriate values in each of these methods, based on which array you need to use for that section.
I hope this helps!
I have a multi-section tableview. In edit mode I allow rows to be moved from one section to another. Once the final row is removed from one section I delete that section. So I am using deleteSection inside moveRowAtIndexPath.
When the final item is moved from the section, the section header disappears as planned. But there is a very strange animation bug, where the moved row seems to 'merge' with the row it is dropped above, and an empty row is displayed at the bottom of the 'to' section (probably because the numberOfRows for that section is correct, but 2 rows are in the same position). Even stranger, when I click the reorder control for this row (not moving the item, simply touching and releasing), the two items 'unmerge'.
I have posted a video demonstrating this.
I have tried wrapping my data changes and view changes in begin/end updates, but to no avail.
I have uploaded a test project here, and I will also post the code below. A couple of points:
I have tried to replicate my data source's format in the demo project, in case this is where the problem originates. The key thing is that my source is a composite array of two other arrays (though I can't see why this would be an issue).
To see the behavior in question, move the two rows in the bottom section, up into the top section. Don't drop them in the last row on the top section though, since this seems to work ok.
Moving rows the other way, from the top section to the bottom section, is buggy in this demo project.
Code (all of this is in the demo project):
I set up my arrays in loadView:
- (void)loadView{
array1 = [NSMutableArray array];
[array1 addObject:#"test 0"];
[array1 addObject:#"test 1"];
[array1 addObject:#"test 2"];
array2 = [NSMutableArray array];
[array2 addObject:#"test a"];
[array2 addObject:#"test b"];
[super loadView];
}
I also have a method that returns a combination of these arrays - this is used as the data source:
- (NSMutableArray *)sourceArray{
NSMutableArray *result = [NSMutableArray array];
if (array1.count > 0) {
[result addObject:array1];
}
if (array2.count >0) {
[result addObject:array2];
}
return result;
}
Which allows for very simple number of rows/sections:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return self.sourceArray.count;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [[self.sourceArray objectAtIndex:section] count];
}
Standard Cell/Header formatting:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
cell.textLabel.text = [[self.sourceArray objectAtIndex:indexPath.section] objectAtIndex:indexPath.row];
return cell;
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
return [NSString stringWithFormat:#"Section %i", section];
}
This is where I do the magic
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
NSMutableArray *fromArray = [self.sourceArray objectAtIndex:fromIndexPath.section];
NSMutableArray *toArray = [self.sourceArray objectAtIndex:toIndexPath.section];
NSString *movedObject = [[self.sourceArray objectAtIndex:fromIndexPath.section] objectAtIndex:fromIndexPath.row];
[fromArray removeObject:movedObject];
[toArray insertObject:movedObject atIndex:toIndexPath.row];
if ([self.tableView numberOfRowsInSection: fromIndexPath.section] == 0) {
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:fromIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
}
}
I notice that the row that comes from the to-be-deleted section is the one that disappears until you retouch the order control.
I suspect that when this datasource method is called by the tableview, its state is still in the middle of performing the move, so calling 'deleteSections' will make the table try and delete the row you're moving. It's not so much of a merge as the fact that it's fading away at the same rate as the section header, and the one below it is just scooting back up to fill the space.
Tapping the control causes the table view to rejigger itself and realize that the row isn't actually gone.
to try and work around this, try running the deletion in the next runloop, via a dispatch call, like:
if ([self.tableView numberOfRowsInSection: fromIndexPath.section] == 0) {
dispatch_async(dispatch_get_main_queue(), ^() {
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:fromIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
});
}
this will cause the deletion to run on the main thread still, but allow the 'moveRow' and whatever call stack it happens to be in finish up its logic before the deletion call
Your problem is in the animation. One is being done while another is not yet finished (moving & deleting animation) causing one cell to be drawn upon the other. You can verify this by moving the cells around again. The correct order will then be displayed. According to Apple's docs on the UITableView:
Note: The data source should not call setEditing:animated: from within its implementation of tableView:commitEditingStyle:forRowAtIndexPath:. If for some reason it must, it should invoke it after a delay by using the performSelector:withObject:afterDelay: method.
Therefore to fix this, do this to your code:
if ([self.tableView numberOfRowsInSection: fromIndexPath.section] == 0) {
[self performSelector:#selector(someMethod:) withObject:fromIndexPath afterDelay:1.0];
}
- (void) someMethod:(NSIndexPath *) fromIndexPath {
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:fromIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
}
Should work fine. Just change the delay to something shorter that suites you.
On the off chance that your rows or what's inside them can take focus, have you checked that you have called resignFirstResponder or [view endEditing:YES]? We saw this when we used text fields and (IIRC it was iOS 4 version dependent too) left the focus in one of the fields.
You have to reload the tableview after deleting the section. Try this code.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
NSMutableArray *fromArray = [self.sourceArray objectAtIndex:fromIndexPath.section];
NSMutableArray *toArray = [self.sourceArray objectAtIndex:toIndexPath.section];
NSString *movedObject = [[self.sourceArray objectAtIndex:fromIndexPath.section] objectAtIndex:fromIndexPath.row];
[fromArray removeObject:movedObject];
[toArray insertObject:movedObject atIndex:toIndexPath.row];
if ([self.tableView numberOfRowsInSection: fromIndexPath.section] == 0) {
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:fromIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
[self.tableView reloadData];
}
}
Swap the order of fromArray and toArray in your code. If the item has a retain count of 1 prior to removing it from the array, it will have a retain count of 0 before adding it to toArray.
If you swap the order, the item will go from retain count of 1 to 2 then back to 1 when the remove is complete.
I think the UITableViewRowAnimationFade animation is interfering with the UITableViewCell move animation. One thing you can try is to delay the section deletion a little bit late in order for the cell move row animation to finish.
Try replace your code with the following code.
-(void)deleteSection:(NSIndexSet*)indexSet
{
[self.tableView deleteSections:indexSet withRowAnimation:UITableViewRowAnimationFade];
}
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
NSMutableArray *fromArray = [self.sourceArray objectAtIndex:fromIndexPath.section];
NSMutableArray *toArray = [self.sourceArray objectAtIndex:toIndexPath.section];
NSString *movedObject = [[self.sourceArray objectAtIndex:fromIndexPath.section] objectAtIndex:fromIndexPath.row];
[fromArray removeObject:movedObject];
[toArray insertObject:movedObject atIndex:toIndexPath.row];
if ([self.tableView numberOfRowsInSection: fromIndexPath.section] == 0) {
[self performSelector:#selector(deleteSection:) withObject:[NSIndexSet indexSetWithIndex:fromIndexPath.section] afterDelay:1.0];
// [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:fromIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
}
}
a solution that lost animation on last row :
if([listOfItemsOnTransaction count]==indexPath.row){
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath, nil]
withRowAnimation:UITableViewRowAnimationFade];
[self.tableView reloadData];
}else
{
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObjects:indexPath, nil]
withRowAnimation:UITableViewRowAnimationFade];
}
Is there any method in the UITableView for the tableviewcell when you are sliding the tableview and cells are being hidden or deleted. I have this code:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
int curIndex = 0;
for (int i = 0; i < [dataHolder.dateArray count]; i++)
{
if ([[dataHolder.dateArray objectAtIndex:i] isEqual:[dataHolder.allDates objectAtIndex:[indexPath section]]])
{
if ([self indexHasContains:i] == NO)
{
curIndex = i;
[indexHasChossen addObject:[NSString stringWithFormat:#"%i", i]];
break;
}
}
}
cell.selectionStyle = UITableViewCellSelectionStyleGray;
cell.textLabel.text = [NSString stringWithFormat:#"%#, %#", [dataHolder.courseArray objectAtIndex:curIndex], [dataHolder.placeArray objectAtIndex:curIndex]];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
cell.detailTextLabel.text = [NSString stringWithFormat:#"%#", [dataHolder.timeArray objectAtIndex:curIndex]];
cell.selectionStyle = UITableViewCellSelectionStyleGray;
cell.textLabel.textColor = [UIColor blackColor];
cell.detailTextLabel.textColor = [UIColor whiteColor];
return cell;
}
I also want a method that delets from the indexHasChossen array when a cell is being hidden/deleted. I have looked through the apple dokumentation and haven’t find anything yet. Do any one know any way to do this?
It doesn't matter how tableView:cellForRowAtIndexPath: if you want to hide or delete cells. The table view calls this method only when it knows cells exist. It depends on what you return in the methods numberOfSectionsInTableView: and tableView:numberOfRowsInSection: method. Most of the times the former returns 1 so if you want to eliminate an entire section than you should've some kind of marker such as sectionHidden which is boolean value indicating whether section is hidden or not.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
if ( sectionHidden )
return 0;
else
return 1;
}
and wherever you want to initiate the delete action do something like this,
sectionHidden = YES;
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0]
withRowAnimation:UITableViewRowAnimationFade];
and to flip it back on do sectionHidden = NO and call reloadSections:withRowAnimation:.
Same thing applies for rows, where you will have to alter the tableView:numberOfRowsInSection: method to reflect that you've deleted the rows or hidden the rows. This time you've to use reloadRowsAtIndexPaths:withRowAnimation: instead of reloadSections:withRowAnimation: method.
Although there's no standard concept of "hidden" tableViewCells, cells deleted by the user are reported in tableView:commitEditingStyle:forRowAtIndexPath:
But let me also add that you seem to be tracking "hasChosen" in cellForRowAtIndexPath . This method only means that the cell is about to appear on screen, not that it's been chosen. "Chosen" occurs when your delegate is called with tableView:didSelectRowAtIndexPath:
Edit: ah, maybe by "hidden", you mean that it's gone off-screen. No, I don't believe there is such a call, (although you could cheat a bit and look at any dequeued cells you get, as those are cells that were formerly on-screen and are now available).
Deleting cells from uitableview is easy. I recommend taking a look on the iPhoneCoreDataRecipes project from the apple developer docs.
You will have to add a function called commitEditingStyle to your UITableViewDelegate, and add the edit button (self.editButtonItem in UITableViewController) to allow editing mode.
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the object for the given index path
}
}
I'm having a UITableView with alternating colored UITableViewCells. And the table can be edited: rows can be reordered and deleted. How do I update the cells alternating background color, when the rows get reordered or deleted?
I'm using this to draw the alternating colored cells:
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
if ([indexPath row] % 2) {
// even row
cell.backgroundColor = evenColor;
} else {
// odd row
cell.backgroundColor = oddColor;
}
}
But this method is not being called when a row gets reordered or deleted. And I can't call [tableView reloadData] from the following method, because it crashes the app in an infinite loop:
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
// Move the object in the array
id object = [[self.list objectAtIndex:[fromIndexPath row]] retain];
[self.list removeObjectAtIndex:[fromIndexPath row]];
[self.list insertObject:object atIndex:[toIndexPath row]];
[object release];
// Update the table ???
[tableView reloadData]; // Crashes the app in an infinite loop!!
}
Does anybody have a pointer or a best practices solution to deal with the issue of reordering alternating colored cells?
Thanks
Used a delayed call to perform the reload if you can't call from that method:
[tableView performSelector:#selector(reloadData) withObject:nil afterDelay:0.0f];
It waits until after your current method is finished before it calls reload.
No needs to use third-party objects or reload/refresh the whole dataSource. Just use the right tools in your swiss knife:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if(editingStyle == UITableViewCellEditingStyleDelete) {
//1. remove your object
[dataSource removeObjectAtIndex:indexPath.row];
//2. update your UI accordingly
[self.myTableView beginUpdates];
[self.myTableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationRight];
[self.myTableView endUpdates];
//3. obtain the whole cells (ie. the visible ones) influenced by changes
NSArray *cellsNeedsUpdate = [myTableView visibleCells];
NSMutableArray *indexPaths = [[NSMutableArray alloc] init];
for(UITableViewCell *aCell in cellsNeedsUpdate) {
[indexPaths addObject:[myTableView indexPathForCell:aCell]];
}
//4. ask your tableview to reload them (and only them)
[self.myTableView reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];
}
}
Reload is too heavyweight; I've written AltTableViewController that just changes background color of cells and it should work faster.
I took all the UITableViewCell subviews from the tableview and sorted that array based on cells frame.origin.y so they were back in the proper order. Then I looped through changing the background color based on the index == 0 || index % 2 == 0 re-coloring them. Seems to work better than reloading the tableView as that was causing the animation to jerk. Worked for me at 1:25 AM
[tableView reloadData] will get your table backgrounds back in the swing of things. Your other option is to swap the background colors of the all visible cells from the indexPath of the lower index in the move on up to the highest in visibleCells.
This works nice. Start the pattern at the last index rather than the first. That way each cell always retains it's background:
if (dataSource.count - indexPath.row) % 2 == 0 {
cell.backgroundColor = UIColor.grayColor()
} else {
cell.backgroundColor = UIColor.whiteColor()
}
I tried the other solutions, but wasn't completely satisfied. This solution is not a hack and doesn't even add another line of code.
If you're using swift and NSFetchedResultsController:
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
tableView.endUpdates()
//for the alternate colours
self.tableView.reloadRows(at: tableView.indexPathsForVisibleRows!, with: .fade)
}