i seem to be having some difficulty trying to access a particular cell, i just need to change one of its objects when i select it in the tableview. There must be a way more efficient way than just calling reloadData all over again. Because thats the only way i could make a table cell look different, by rebuilding it when i select on one. Thanks for all the help :)
[self updatePreferences];
[tableView reloadData];
This is all i have atm on the method where it handles the interaction with table cells.
Use the following code.To reload a single cell.
NSArray *array = [NSArray arrayWithObject:[NSIndexPath indexPathForRow:row inSection:section]];
[self.tableView reloadRowsAtIndexPaths:array withRowAnimation:UITableViewRowAnimationNone];
You could also make the cell a custom one and add a method to it like update or refresh.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
CustomCell *cell = [tableView cellForRowAtIndexPath:indexPath];
[cell refresh];
}
Related
I have a tableview in a scrollview in a popover. When the view is presented, the bottom cell in tableview is not visible to the user. If I select all of the cells then deselect the fist cell, the out of view cell is deselected too. Has anyone come across this behaviour before? If so, how to approach it?
Now your job is to find all the visible cells in the tableview and then apply select/deselect to it.
UITableView *tableView = self.tableView;
// Or however you get your table view
NSArray *paths = [tableView indexPathsForVisibleRows];
// For getting the cells themselves
NSMutableSet *visibleCells = [[NSMutableSet alloc] init];
for (NSIndexPath *path in paths)
{
[visibleCells addObject:[tableView cellForRowAtIndexPath:path]];
}
// Now visibleCells contains all of the cells you care about.
-(void) tableView:(UITableView *)tableView didDeselectRowAtIndexPath:
(NSIndexPath *)indexPath {
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
- (void) tableView:(UITableView *)tableView didSelectRowAtIndexPath:
(NSIndexPath *)indexPath {
//stuff
//as last line:
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
For that matter, deselectRowAtIndexPath can be called from anywhere at any time you want the row to be deselected.
[self.myTableView deselectRowAtIndexPath:[self.myTableView
indexPathForSelectedRow] animated: YES];
If you are using dequeueReusableCellWithIdentifier: change your cellForRowAtIndexPath: to use dequeueReusableCellWithIdentifier:forIndexPath:
In a UITableView cells get reused. That means it only produces as many as absolutely needed. As soon as a new one is coming onto the screen, the last one is "recycled" instead of initialising a whole new instance.
This makes your application run faster. It also means that you have to undo any changes you made, when recycling.
Selection status is one of them. The UITableView should manage this automatically for you, if it is dequeued with the relevant indexPath. If not, it wouldn't know whether that specific cell should be selected.
Let's start right off with some code :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"forIndexPath:indexPath];
Produit *object = self.objects[indexPath.row];
[cell.contentView addSubview:object];
return cell;
}
In a cell, I add a subView of type Produit, which is a subclass of UIView. This is how it looks like:
Editing all the stuff works fine except for when there are more cells than the size of the screen can allow. When that is the case, if I try and modify some info in one of the cells, it's as if the new info is added on top of the old one like this:
In this image, only the Button acts spooky but sometimes the text fields also appear on top of each other. What's more is that if I modify the cell on top, then if I scroll to the bottom of the table view, the last cell also gets modified. Last thing: when I add more cells after having produced this glitch, some of the new cells get the same 'Category' as the glitched one, it's like it's making a copy of it and puts in 'Category' the glitched title...
Can someone explain what's happening? How can I fix it? Here is some more code( not all of it, just the table view configuration)
-(void) addNewProduit:(UIBarButtonItem*) item {
if (!self.objects) {
self.objects = [[NSMutableArray alloc] init];
}
Produit* product = [[Produit alloc] init];
CGRect frame = CGRectMake(0, 0, self.frame.size.width, 44);
[product setFrame:frame];
[product initView];
[self.objects insertObject:product atIndex:0];
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:0 inSection:0];
[self.tableView insertRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
}
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath {
// Return NO if you do not want the specified item to be editable.
return YES;
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
if (editingStyle == UITableViewCellEditingStyleDelete) {
[self.objects removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
} else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
}
}
dequeueReusableCellWithIdentifier: forIndexPath: gives you a cell, which might be a new cell, or it might be an old cell that's previously been shown, but has scrolled off the screen.
One quick fix is:
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"forIndexPath:indexPath];
Produit *object = self.objects[indexPath.row];
[cell.contentView.subviews makeObjectsPerformSelector:#selector(removeFromSuperview)];
[cell.contentView addSubview:object];
return cell;
This will resolve your issue in the least efficient way possible. It is likely to cause jittery animation when you scroll really fast, especially on older devices. I just intend it as an illustration of the problem you need to solve.
A more appropriate solution would reuse the view if it's already there, instead of creating a new one each time.
self.objects appears to contain views, which defeats the purpose of UITableView's really fast scrolling setup. You should just include data objects there, and then configure the views for an individual cell when it's time to show that one cell. IE, you don't want a view for each data object, you want 6 views that adapt to which data object currently needs to be displayed.
You are always adding more views when you re-use a cell by [cell.contentView addSubview:object];. One solution might be to tag the view when you add it and then remove any subview with the appropriate tag before adding another one.
Using this code
- (IBAction)testAdd:(id)sender
{
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:self.numberOfRows inSection:0];
[self.tableView beginUpdates];
self.numberOfRows++;
[self.tableView insertRowsAtIndexPaths:#[indexPath]withRowAnimation:UITableViewRowAnimationBottom];
[self.tableView endUpdates];
}
I'm able to add a new item to a tableView via an 'add' button on the app. This basically adds an item identical to the item already on the table that preceded it.
For example, I have a tableview with the first row displaying a string "TEST", hitting add adds another row that displays "TEST".
I would like to be able to pass in a custom value for the new row, so hitting add outputs a row with say "NEWTHING".
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"UITableViewCell" forIndexPath:indexPath];
// Configure the cell...
cell.textLabel.text = self.val2;
return cell;
}
My data source is actually another view controller that takes user inputs and sends it to my tabelViewController, with the text for the item as "val2".
What I actually want to achieve is the ability to hit add, go back to the user input view controller, get the new data and send it back to my tableViewController to be displayed
What you're asking, is the kinda stuff that is to be done in -cellForRowAtIndexPath: (most of the times, it depends on the way you have designed your datasource) but if it doesn't matter to you, then you can do:
- (IBAction)testAdd:(id)sender
{
NSIndexPath *indexPath = [NSIndexPath indexPathForRow:self.numberOfRows
inSection:0];
self.numberOfRows++;
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:#[indexPath]
withRowAnimation:UITableViewRowAnimationBottom];
[self.tableView endUpdates];
UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
[cell.textLabel setText:#"NEWTHING"];
}
But note that when you scroll far up/down and return to this cell, it will most probably show "TEST" (that's where -cellForRowAtIndexPath: will show it's true purpose)
PS: Include your -cellForRowAtIndexPath: method implementation in the question if you want to proceed further
EDIT:
Your -cellForRowAtIndexPath is too static... in the sense that it simply sets self.val2 to cell.textLabel.
Lets say you start with 10 rows, -cellForRowAtIndexPath will be called 10 times and every time, it will set self.val2 onto the current cell's textLabel.
Now... when you add one row (on a button tap), the -cellForRowAtIndexPath will be called for the 11th cell and the same* text will be set to it.
*this technically happened but we quickly changed the cell's text
Basically, the tableView doesn't know how to differentiate between an existing cell and a new added cell because the datasource itself is not dynamic.
To direct the tableView on how to handle different cells, we need to create a more dynamic datasource.
There are different approaches use but I'd generally do it this way:
- (void)viewDidLoad
{
[super viewDidLoad];
self.val2 = #"TEST";
//declare "NSMutableArray *arrDatasource;" globally
//this will be the soul of the tableView
arrDatasource = [[NSMutableArray alloc] init];
int i_numberOfCells = 10;
//populate beginning cells with default text
for (int i = 0; i < i_numberOfCells; i++) {
NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
[dictionary setObject:self.val2 forKey:#"displayText"];
[arrDatasource addObject:dictionary];
}
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
//return number of objects in arrDatasource
return arrDatasource.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"UITableViewCell" forIndexPath:indexPath];
//pick up value for key "displayText" and set it onto the cell's label
[cell.textLabel setText:arrDatasource[indexPath.row][#"displayText"]];
//this will be dynamic in nature because you can modify the contents
//of arrDatasource and simply tell tableView to update appropriately
return cell;
}
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
//make indexPath of new cell to be created
NSIndexPath *indexPathNEXT = [NSIndexPath indexPathForItem:arrDatasource.count inSection:0];
//add the appropriate contents to a dictionary
NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
[dictionary setObject:#"NEWTHING" forKey:#"displayText"];
//add the dictionary object to the main array which is the datasource
[arrDatasource addObject:dictionary];
//add it to tableView
[self.tableView beginUpdates];
[self.tableView insertRowsAtIndexPaths:#[indexPathNEXT]
withRowAnimation:UITableViewRowAnimationAutomatic];
[self.tableView endUpdates];
//this ends up calling -cellForRowAtIndexPath for the newly created cell
//-cellForRowAtIndexPath shows the text (you put in the dictionary in this method above)
}
PS: -cellForRowAtIndexPath: is called whenever cell updates or refreshes or needs to be displayed and so this method needs to be implemented properly
I have an app in which I have a UITableview with custom cells and headers. The cells have an inputView so when selected they become first responder and allow the user to input data.
I want to be able to update the visible TableViewCell and header information on the fly while the user is changing it.. easy, just call [tableview reloadData]; ..
Unfortunately this causes the inputview to resign first responder and hide itself.
Is there any way that I can get a reference to the cell itself inside the UITableview so that I can just change the text property? (cellForRow:atIndexPath: returns a new object with the same properties so doesn't work) It seems like the only easy solution may be to store a reference the cells in a dictionary each time a cell is populated, not really the ideal solution.
cellForRowAtIndexPath is literally just
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
CustomCell *orderCell;
static NSString *productCellIdentifier = #"ImageDetailCellIdentifier";
orderCell = [self.tableView dequeueReusableCellWithIdentifier:productCellIdentifier forIndexPath:indexPath];
//set a bunch of properties orderCell.blah
return orderCell;
}
According to UITableView documentation, -cellForRowAtIndexPath: returns an object representing a cell of the table or nil if the cell is not visible or indexPath is out of range.
That is also how I remember it. I don't think your observation is correct that it returns a new object. If the cell is visible you will get hold of it.
[tableView beginUpdates];
[tableView reloadRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade]; ///as your choice in animation
[tableView endUpdates];
or else
[tableView beginUpdates];
// do some work what ever u need
[tableView endUpdates];
For reloading specific rows, you can use
- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation;
For example,
NSIndexPath* indexPath = [NSIndexPath indexPathForRow:2 inSection:1];
NSArray* indexArray = [NSArray arrayWithObject:indexPath];
[self.tableView beginUpdates];
[self.tableView reloadRowsAtIndexPaths:indexArray withRowAnimation:UITableViewRowAnimationFade];
[self.tableView endUpdates];
I have a tableView that I have set allowsMultipleSelection to YES in storyboard.
EDIT
I was wrong about one thing... [tableView indexPathsForSelectedRows] does return a NSArray with 1 object in it during didSelectRowAtIndexPath.
However it does not work in cellForRowAtIndexPath after I reload the table so it will check which accessory (check mark or not) to apply.
In the original question I was trying to manually select the rows... Apparently that is handled by the tableView itself.. but somewhere along the way it is automatically deselecting my row as I never call deselectRowAtIndexPath on it...
Original Question:
For some reason when I set the cell to selected it does not change.
- (void)tableView:(UITableView *)tableView
didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
//cell does not update selected property to YES after this next line
cell.selected = YES;
[tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
}
I suppose I can keep track of the selected index paths myself... but I can swear I used a method that involved indexPathsForSelectedRows previously with success...
You cannot set the selected property directly
So instead of
cell.selected = YES;
Use
[tableView selectRowAtIndexPath:TheIndexPAth animated:YES scrollPosition:UITableViewScrollPositionBottom];
please post your all codes for this class in pastbean and put your link here we need more information,
and also try:
//in your interface
#interface YourClass (){
NSInteger _selectedIndex;
}
// cellForRowAtIndexPath: method
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath
*)indexPath
{
UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
// didSelectRowAtIndexPath: method
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
_selectedIndex = indexPath.row;
[self.tableView reloadData];
}
Try [cell setSelected:YES animated:YES]
I'm pretty sure cell.selected is read only
A bit unfair since the question changed but.. for me.. the answer is either don't use
indexPathsForSelectedRows
or don't call
reloadTable
on your tableView.
I opted for the later, I decorated the accessory in didSelectRow and didDeselectRow instead of doing it on reload and just never reloading the table.
If someone can come up with a solution that involves both of the above, I will select that answer instead.