I'm not quite sure what's going on here but I'm running into a contact form that I'm working with. In my form I've added the ability to add an email address to a contact. As pictured below, once the user clicks on "add email", a row is added to the "Emails" section.
However after I click to delete the email, an extra cell appears underneath the add email button (pictured below).
There's a little red box from what appears to be the prior delete cell as though the table isn't reloaded. Here's my delete code:
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if( editingStyle == UITableViewCellEditingStyleDelete )
{
// Update the data source
NSMutableArray *fields = (NSMutableArray *)self.fields[#(indexPath.section)];
[fields removeObjectAtIndex:indexPath.row];
NSMutableArray *values = (NSMutableArray *)self.values[#([self fieldTypeAtIndexPath:indexPath])];
[values removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationMiddle];
}
}
So why is that cell remaining afterwards? I can call [tableView reloadData] within the method above and it removes the excess cell but then it messes up the animation. Can you shed some clarity on what I'm doing wrong here?
This looks like a bug.
I just noticed that even Apple has this same bug in their Reminders app. It seems to be related to deleting rows from a UITableView with variable height items.
In Apple's Reminders app, when you delete something from a long list with variable height items, you will see the same exact visual artifact for a split second. Then the table jumps and the list looks correct. I am assuming Apple just reloads the entire table view a second after the item is removed in order to fix the visual glitch.
My recommendation is to report this as a bug to Apple. For now you can reload the entire table view like Apple presumably does.
Option 1: Before you call deleteRowsAtIndexPaths, you must make sure that numberOfRowsInSection will return the correct value (e.g. if you originally had 2 rows in that section, it should now return 1 row).
Option 2: If that isn't the problem, I would try a different animation type (e.g. UITableViewRowAnimationAutomatic), just to see if that has any effect.
Option 3: Ensure that cellForRowAtIndexPath is returning a valid cell with its contents being reset. Otherwise it may be reusing an invalid cell or displaying something that was there before.
Option 4: Since the heights are different, ensure that heightForRowAtIndexPath is returning the correct value. You probably need to call reloadRowsAtIndexPaths in order for the table view to know about the height difference.
I had the same problem and I guess it might be a bug in iOS7 where it doesn't repaint the cells correctly, I fixed it but not in an efficient way, just in the "cellForRowAtIndexPath" , always create a new cell, don't dequeue it.
Related
I am having a strange problem. When I add a record to entities i.e. core data from certain screens, the table view instead of showing the new record, repeats the previous record.
It always happens with some entities and screens, i.e. if I add records, 1,2,3 etc. it will display 1,1,1. With other screens and entities that use identical code, it sometimes happens, usually after about the eight through tenth record.
In these cases, if I add records named 1,2,3…10, it will display 1,2,3,4,5,6,7,8,8,8,8,8,8 etc.
Has anyone ever encountered this strange/spooky behavior? Why would it think that the new record is the same as the previous record either right away or at some point i.e. when the number of records hits 8 or so?
Note, it saves fine in core data as when I close the simulator and rebuild, it shows the right records.
The delegate pattern also seems to be working—somewhat—as it shows a new record when one is added, only it shows a copy of the last record and then the record on which it got stuck, i.e. 8,8,8 etc.
Thanks for any suggestions. This has been driving me crazy for a week now.
Am posting without code as SO will not accept the code I posted for some reason... Happy to post any code requested.
Edit:
#pragma mark - Table view data source
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:#"Cell"];
Lists *list = [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = list.listname;
cell.detailTextLabel.text = list.list;
return cell;
}
In response to Duncan:
Apple's documentation states:
"A delegate must implement at least one of the change tracking delegate methods in order for change tracking to be enabled. Providing an empty implementation of controllerDidChangeContent: is sufficient."
My code includes:
#pragma mark - NSFetchedResultsControllerDelegate
-(void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
//change
}
I know there is a more verbose method with will change content and did change content with a switch statement for different cases but the documentation says that is not necessary. (I also tried it and it did not fix problem.) I declare the list file as the delegate in the header with:
#interface ListsVC : UITableViewController<UITableViewDataSource, UITableViewDelegate,NSFetchedResultsControllerDelegate>
For me, it's a bug in the TableView.
In fact, the last row is twice displayed but the "last" row is empty.
I solved the problem by adding this code in my linked css (fill empty rows whit the same background and text-fill color and remove the borders.
It works fine!
.table-row-cell:empty .table-cell
-fx-border-width: 0px;
-fx-background-color: white;
-fx-text-fill: white;
My current set up is the following:
Root Tab Bar:
Collection view with magazines
Bookmarks (with a table view)
Others
You can add a bookmark from a magazine in the collection view and also remove it from there.
The behaviour I'm seeing is the following:
I start the application, the table view queries the number of sections, number of cells, but not the cellForRowAtIndexPath. I could understand why, as there is no cell in the active view, so no data should be loaded.
When I add a bookmark from the collection view, it adds it to the array (via a notification) and requests the tableview to be reloaded. As there isn't an initial entry, it goes through the motions described above. When I press it again to remove the bookmark the entry is removed from the array. This is where it gets interesting because the first thing the table calls is not the number of sections or rows but the cellForRowAtIndexPath. As the array is empty, the application crashes on a request for data on index 0.
My question is why does the cell creation get called in that order? Is there any way to avoid it?
If you changed the section, try calling - (void)reloadSections:(NSIndexSet *)sections before you call reloadData
https://developer.apple.com/library/ios/DOCUMENTATION/UIKit/Reference/UICollectionView_class/index.html#//apple_ref/occ/instm/UICollectionView/reloadSections:
[self.tableView reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationLeft];
The reason this was happening is because I was attempting to change something about the table before I reloaded the data.
[self.tableView setSeparatorStyle: !_helpText.hidden ? UITableViewCellSeparatorStyleNone : UITableViewCellSeparatorStyleSingleLine];
[self.tableView reloadData];
That was for removing the lines so a message can be displayed. However that update was using old data as reloadData had not been called.
[self.tableView reloadData];
[self.tableView setSeparatorStyle: !_helpText.hidden ? UITableViewCellSeparatorStyleNone : UITableViewCellSeparatorStyleSingleLine];
Reversing them fixed the issue.
I understand the concepts of cell re-usability for Xcode 5.0 table views. However, I have one very weird observation which I don't understand and wish anyone of you could enlighten me here. Thanks.
I have implemented a table view with a search bar utility (just on top of the table view). Under each custom cell (prototype cell), whenever a user clicks on it, it will be marked with a checkmark (UITableViewCellAccessoryCheckmark). The number of cells are more than 10.
Observation:
- Without using any search, marking and unmarking a cell is working as intended. Cells are updated instantly along with their checkmarks.
- When doing a search, from the results given, marking and unmarking a cell is also working as intended.
[Problem] Here comes the weird issue: when cancelling a search, an already marked cell (marked during search) does not refresh itself in the tableview unless scrolling up or down is performed!
And hence, I wrote [tableview reload] at the end of tableview:didSelectRowAtIndexPath: method. Obviously, it doesn't refresh the tableview for me. Without further changing any other code, merely modifying [tableview reload] to [self.tableview reload] under the same method works!
Why is the only addition of "self." able to make the table cells refreshed instantly? I have always thought the first argument, tableView, from the method (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath is as equal to self.tableview. Obviously, my interpretation in this case is wrong.
Thank you. I'm sorry for my lengthy post.
My guess is that this UISearchBar comes from a UISearchDisplayController. Is that correct?
If true, that is a common misconception, but an easy one to understand.
When filtering your UITableView entries and showing results, UISearchDisplayController actually overlays the view with its own tableView, UISearchResultsTableView.
Thus, this overlaid tableView also gets to call data source and delegate methods on your implementation, and this is when the tableView argument from tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath stops being equivalent to self.tableView.
This means that calling [tableView reloadData] during filtering actually asks UISearchResultsTableView to reload its contents, not self.tableView, a property of your viewController.
I have several cells that are written onto a UICollectionView and reloading them takes a long time. How can I reload only when the data of a cell is modified? Here's one thing I've tried:
if([oldDataSource count] != [currentDataSource count])
{
[collectionView reloadData];
}
Yet, I still don't want to deal with reloading the entire thing. I've also tried:
if([oldDataSource count] < [currentdataSource count])
{
//something was added. //reload the last item in the current data source
}
This also failed because I can't reload something that doesn't "exist" in memory yet. This method also doesn't work because if something was deleted from my data source, the Cell will still remain in the interface, and will crash if clicked on.
So, what's the best way to deal with edited cells?
Thanks!
Reloads just the items at the specified index paths.
- (void)reloadItemsAtIndexPaths:(NSArray *)indexPaths
Discussion
Call this method to selectively reload only the specified items. This causes the collection view to discard any cells associated with those items and redisplay them.
try and get the cell u want to change. then:-
If u can get it. change the data source and reload it.
if it doesnt reflect the changes. change the data source, then the repective new values of the cell, then call setNeedsDisplay on the cell.
If the cell is not returned (that means) it is out of the view. Simply change the data source. The change in the data source will be reflected when the cell is brought to view
try any of these three.
cheers. have fun
I have a problem that is driving me crazy.
I have an UITableView that is always in editing mode (it has to be).
The user can add new rows to it.
The navigationItem.leftbarButton of the tableViewController pushes a new controller just to do it, let's call it "newRowsVC".
Before the push the tableViewController set itself as the delegate of the newRowsVC, the protocol has only a method:
-(void) aNewRowHasBeenCreated
{
[self.tableView reloadData];
}
I start adding rows and everything works fine, each now row is immediately displayed in the tableViewController until the last new row will force the tableView to scroll because there won't be anymore screen real estate for it. Here, I have no idea why, the tableView, only it, is as frozen, with no scrollbar and doesn't respond to input. The app continues to run without a crash and I can even dismiss the tableViewController by tapping the navigationItem.rightbarButtonItem.
I can keep creating new rows, they are added to the array, the number of row in the tableView data source is computed correctly. But the table is like dead.
If I dismiss the tableViewController and then I come back to it, I see that all the rows previously created, also the ones not shown as soon as they were created are there!
I really do not have idea of how I can fix this.
The first thing I tried was to force the scroll after the reload of the table but it didn't fix it.
-(void) aNewRowHasBeenCreated
{
[self.tableView reloadData];
[self.tableView setScrollEnabled:YES];
}
I also tried forcing the tableView to scroll to the last row but it didn't fix it.
-(void) aNewRowHasBeenCreated
{
[self.tableView reloadData];
[self.tableView setScrollEnabled: YES];
[self.tableView scrollToRowAtIndexPosition: [self.tableView indexPathsForVisibleRows]last object] atScrollPosition: UITableViewScrollPositionBottom animated:YES];
}
I check the number of rows each time the table is reloaded. No error, the number is perfect and the new rows data are correctly in the array, also the data for the cells not shown.
I thought it could be because the tableView is always in editing mode so I tried setting it to NO but nothing changes, id din't fix the problem.
Two notes:
1)the tableView has to be the delegate of each one of it's custom cells. They have an UITextField and an UIStepper, handled by the tableViewController. I already tried to not set the tableViewController as the delegate of its custom cells but nothing changes so the problem is not this.
2) self.tableView.bounces = NO but this has nothing to do with the scrolling issue, the scroll is enabled.
Update: After more tests I found that if I remove the dequeue of the reusable custom cell everything works fine, so the problem should be about the reuse.
static NSString *CellIdentifier=#"MyCell"
CustomCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier];
Nicola
After hours I got it. As pointed out by Amit the problem was hidden in cellForRowAtIndexPath... It was hard to catch because it didn't happened all the times and the first times I enabled/disabled the cell reusing everything seemed the same so I did not link the problem to it. I got back on it after I tried about all the other options I had been able to think about.
The problem was in the reuse of the cells and the fact that the custom cell has the tableView as its delegate to handle its textView and the stepper without exposing them.
I got rid of all the delagion stuff and exposed the textView and the stepper as public properties of the view. By doing this I was able to set the tableViewController directly to be the delegate of the cell.textView and to add directly a target/action for the stepper.
Everything works flawslessly now.
Thanks to everyone who tried to help me!
Nicola