I have a UITableView. I want to update the table data based on selection made. Right now I use [mytable reloadData]; I want to know if there is any way where I can just update the particular cell which is selected. Can I modify by using NSIndexPath or others? Any suggestions?
Thanks.
For iOS 3.0 and above, you just have to call :
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation;
To reload row 3 of section 2 and row 4 of section 3 for example, you'll have to do this :
// Build the two index paths
NSIndexPath* indexPath1 = [NSIndexPath indexPathForRow:3 inSection:2];
NSIndexPath* indexPath2 = [NSIndexPath indexPathForRow:4 inSection:3];
// Add them in an index path array
NSArray* indexArray = [NSArray arrayWithObjects:indexPath1, indexPath2, nil];
// Launch reload for the two index path
[self.tableView reloadRowsAtIndexPaths:indexArray withRowAnimation:UITableViewRowAnimationFade];
You can also get a reference to the UITableViewCell object and change its labels, etc.
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
cell.textLabel.text = #"Hey, I've changed!";
I think you're looking for this method of UITableView:
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation
Related
Here is what I want in my app. Shown below are two screenshots of the iPhone app Store:
I basically need a "Read More" feature just like it is used in the app store (See the "Description" section in the two images above). I am assuming that each section here (Description, What's New, Information etc.) is a table view cell. And the text inside is a UILabel or UITextField.
Here is what I have tried so far to add this feature:
NSString *initialText = #"Something which is not a complete text and created just as an example to...";
NSString *finalText = #"Something which is not a complete text and created just as an example to illustrate my problem here with tableviews and cel heights. bla bla bla";
NSInteger isReadMoreTapped = 0;
My cellForRowAtIndexPath function:
// Other cell initialisations
if(isReadMoreTapped==0)
cell.label.text = initialText;
else
cell.label.text = finalText;
return cell;
My heightForRowAtIndexPath function:
// Other cell heights determined dynamically
if(isReadMoreTapped==0){
cell.label.text = initialText;
cellHeight = //Some cell height x which is determined dynamically based on the font, width etc. of the label text
}
else{
cell.label.text = finalText;
cellHeight = //Some height greater than x determined dynamically
}
return cellHeight;
Finally my IBAction readMoreTapped method which is called when the More button is tapped:
isReadMoreTapped = 1;
[self.tableView beginUpdates];
[self.tableView endUpdates];
NSIndexPath* rowToReload = [NSIndexPath indexPathForRow:2 inSection:0]; // I need to reload only the third row, so not reloading the entire table but only the required one
NSArray* rowsToReload = [NSArray arrayWithObjects:rowToReload, nil];
[self.tableView reloadRowsAtIndexPaths:rowsToReload withRowAnimation:UITableViewRowAnimationNone];
After doing all this, I do get the required functionality. The new height of that particular cell is calculated and the new text loaded into it. But there is a very unnatural jerk on the TableView which results in a bad User experience. That is not the case with the app store More button though. There is no unnatural jerk in its case. The TableView remains at its place, only the changed cell has its size increased with the text appearing smoothly.
How can I achieve the smoothness as done in the iPhone app store More button?
Your problem might come from reloading the row. You want to try to configure the cell properties directly. I usually use a dedicated method to configure my cell content so I don't have to reload rows.
- (void)configureCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
if(isReadMoreTapped==0)
cell.label.text = initialText;
else
cell.label.text = finalText;
// all other cell configuration goes here
}
this method is called from the cellForRowAtIndexPath method and it will configure the cell
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
[self configureCell:cell forRowAtIndexPath:indexPath];
return cell;
}
and you would call this method directly to avoid reloading:
isReadMoreTapped = 1;
[self.tableView beginUpdates];
[self.tableView endUpdates];
NSIndexPath* rowToReload = [NSIndexPath indexPathForRow:2 inSection:0];
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:rowToReload];
[self configureCell:cell forRowAtIndexPath:rowToReload];
Please try the following changes to your code, I think it will fix your problem.
no need to set cell.label.text in heightForRowAtIndexPath; Please remove them.
in the readMoreTapped, update table is enough:
isReadMoreTapped = 1;
[self.tableView beginUpdates];
[self.tableView endUpdates];
Either remove the calls to:
[self.tableView beginUpdates];
[self.tableView endUpdates];
Or change to ensure that your reloading code is between them. I would remove them as a single row reload is handled well with the method you use:
[self.tableView reloadRowsAtIndexPaths:rowsToReload withRowAnimation:UITableViewRowAnimationNone];
You just need to specify a row animation like fade.
Okay, I finally solved the problem with the help of Matthias's answer (the accepted answer) and my own optimisations. One thing that definitely should be done is to create a dedicated function like configureCell: forRowAtIndexPath: to directly configure cell properties (see Mathias's answer). Everything remains the same with Matthias's answer except:
Before, I was calculating the heights of each cell everytime the heightForRowAtIndexPath function was called without caching(saving) them anywhere and hence when [self.tableView beginUpdates]; and [self.tableView endUpdates]; were called each cell height was calculated again. Instead, what you have to do is to save these cell heights in an array/dictionary so that whenever the More button is tapped, you calculate the height of only the cell that was changed. For the other cells, just query the array/dictionary and return the saved cell height. This should solve any problems with the tableView scroll after the cell height update. If anyone else still face a similar issue as this, please comment on this post. I would be happy to help
I'm writing an iPhone app with a UITableView as the primary user interface. Each section consists of two rows, a header and the body. When the user clicks on the header, I remove the second row by changing the numberOfRowsInSection value:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
cbwComponent *comp = [_componentController objectInListAtIndex:section];
if([comp hasContentsView] && !comp.contentsHidden){
return 2;
}else
return 1;
}
When the user selects the header, I'm using the following code:
comp.contentsHidden = YES;
[self.tableView beginUpdates];
NSArray *deleteIndexPaths = [[NSArray alloc] initWithObjects:[NSIndexPath indexPathForRow:1 inSection:indexPath.section], nil];
[self.tableView deleteRowsAtIndexPaths:deleteIndexPaths withRowAnimation:UITableViewRowAnimationFade];
[self.tableView endUpdates];
It's working great, with a nice smooth fade effect. The problem is, I'm trying to add an indicator in the header cell (row 0) that changes when it's clicked on. To change that image I have to refresh the top row as well as the second row, which makes the transition look bad (well, not nearly as smooth). Is there a way to change the image in a UITableViewCell without refreshing the cell?
Thanks
EDIT: I figured it out! You can maintain the smooth transition as long as you reload that first row before you make the change to the second row. It has to be called inside of [tableView beginUpdates];
[self.tableView beginUpdates];
[self.tableView reloadRowsAtIndexPaths:[[NSArray alloc] initWithObjects:[NSIndexPath indexPathForRow:0 inSection:indexPath.section], nil] withRowAnimation:UITableViewRowAnimationNone];
...
[self.tableView endUpdates];
Did the trick.
You could also subclass a tableview cell and implement a view transition in it that can be called from your view controller. You could then call that without having to reload the cell.
[(YourCustomCell*)[tableView cellForRowAtIndexPath:indexPathOfYourCell] fadeInIndicator];
I have a UITableView. I'm population it from a NSDictionary with arrays for each set of items on the table: labels, footers, Headers, UIViews, etc.
In section 0, I want a row #2 appear when a switch in row #1 is switched to on.
What I have done and it works is, in numberOfRowsInSection I added this code:
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
if (interruptor.isOn==NO && section==0) {
return [[[infoTableContentArray objectAtIndex: section] objectForKey:kLabelKey] count]-1;
}else{
return [[[infoTableContentArray objectAtIndex: section] objectForKey:kLabelKey] count];
}
}
and the action linked to the switch (interruptor) is:
-(IBAction)accioInterruptor:(id)sender{
[infoAndSettingsTable reloadData];
}
so when the switch is switched, the table reloads and the cell appears or disappears.
it actually works, but there is no animation, which makes it, mhh... well, you know.
I've tried to implement the reloadRowsAtIndexPaths:withRowAnimation, adding it to the code called by the switch:
-(IBAction)accioInterruptor:(id)sender{
[infoAndSettingsTable beginUpdates];
[infoAndSettingsTable reloadRowsAtIndexPaths:[[infoTableContentArray objectAtIndex: 0] objectForKey:kLabelKey] withRowAnimation:UITableViewRowAnimationBottom];
[infoAndSettingsTable endUpdates];
}
But, it dowsn't work. It crashed on the line [infoAndSettingsTable endsUpdates];
BTW, in all the cases the following:
[[infoTableContentArray objectAtIndex: 0]
is the array which contains the labels for that section.
Am I doing it right or I'm Epic-Failing alltogether?
Thanks in advance!
simple way to do this......
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:insertIndexPaths withRowAnimation:UITableViewRowAnimationFade];
[self.tableView deleteRowsAtIndexPaths:deleteIndexPaths withRowAnimation:UITableViewRowAnimationFade];
[self.tableView endUpdates];
insertIndexPaths is an array of NSIndexPaths to be inserted to your table.
deleteIndexPaths is a array of NSIndexPaths to be deleted from your table.
Example array format for index paths :
NSArray *insertIndexPaths = [[NSArray alloc] initWithObjects:
[NSIndexPath indexPathForRow:0 inSection:0],
[NSIndexPath indexPathForRow:1 inSection:0],
[NSIndexPath indexPathForRow:2 inSection:0],
nil];
got it from this question
the argument to reloadRowsAtIndexPaths: should be an array of NSIndexPath objects identifying the rows you want to reload, not the labels for that section. Also, looks like you want to reload a section so I would try the following:
-(IBAction)accioInterruptor:(id)sender {
[self reloadSections:[NSIndexSet indexSetWithIndex:0] withRowAnimation:UITableViewRowAnimationBottom];
}
Why don't you just use UITableView's insertRowsAtIndexPaths:withRowAnimation:? It has been built exactly for this purpose, the UITableView class reference has the exact description and usage examples.
Apart from being cleaner it is also more performant since you don't have to reload the entire table (only really matters if you have lots of cells in it though)
I have multiple UITableViews in my app, is there a method of detecting which cell/row the user has selected in that column?
Also is it possible to programatically deselect a cell/row?
Thanks.
Get currently selected index path for a table:
NSIndexPath *path = [tableView indexPathForSelectedRow];
Deselect currently selected row:
[tableView deselectRowAtIndexPath:[tableView indexPathForSelectedRow] animated:YES];
These are all easily found in the documentation for UITableView. Perhaps you should look there first next time.
Here's even a link: http://developer.apple.com/library/ios/#documentation/uikit/reference/UITableView_Class/Reference/Reference.html
NSIndexPath *path = [tableView indexPathForSelectedRow];
The above line will throw EXC BAD ACCESS if no sell is selected so keep track of your selected cell with NSIndexPath instance variable and only deselect when it is actually selected with isSelected property of cell.
UITableViewCell *cell = [tableView cellForRowAtIndexPath:someIndexPath];
if(cell.isSelected) {
[tableView deselectRowAtIndexPath:someIndexPath animated:YES];
}
I want to change the textLabel and detailTextLabel of a cell when it has been selected.
I've tried the following, but no change occurs:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
MyAppDelegate *appDelegate = (MyPhoneAppDelegate*)[[UIApplication sharedApplication] delegate];
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
cell.detailTextLabel.text = #"xxxxx";
cell.textLabel.text = #"zzzzz";
[tableView reloadData];
}
I agree, reloading the table view will actually dump and reload/display all the cells using tableView:cellForRowAtIndexPath: and use the original data, not the updated #"xxxxx" and #"yyyyy" in your tableView:didSelectRowAtIndexPath: method.
In a little test project I was able to change the labels upon selection with:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell * cell = [tableView cellForRowAtIndexPath:indexPath];
cell.textLabel.text = #"it was tapped";
}
You should not be trying to reload the table while a cell is selected. Instead, try
[cell setNeedsLayout]
after you make the above changes to the labels.
Also, is there a reason you're making a reference to the app delegate in the method?
Try to reload the cell you selected (described by indexPath) :
[yourTableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationNone];
Create a New iPad Project (Split View) and Now go through the Classes->Files. The easiest way's been given there. The XCode's Generated Codes.
Sample Code Lines :-
cell.textLabel.text = [NSString stringWithFormat:#"Row %d", indexPath.row];
You can use them in cellForRowAtIndexPath ||&& didSelectRowAtIndexPath ..
Not sure what you're trying to do with the delegate but you should try calling the tableView already instantiated; i.e. call
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath: indexPath];
Maybe I'm not clear
What I'm saying is that you are instantiating a new empty table view
UITableViewCell *cell = [**tableView** cellForRowAtIndexPath: indexPath]; //cell has nothing it is new.
consider replacing to call the old
UITableViewCell *cell = [**self.tableView** cellForRowAtIndexPath: indexPath]; //now you have one that has a textField already in it
Did you try to refresh only the selected cell instead of reloading the whole table ?
[cell setNeedsDisplay];
instead of
[tableView reloadData];
This will have better performance and I'm not but I suppose that selection is lost if you refresh the whole table (this may be the reason why you don't see any change in the end)....