I have a tableview with 5 sections and variable number of rows in each section with a custom cell (for check and uncheck images on a cell). When I select a row in first section, tableview also selects any one of the row in the last section.
And when I scroll up and down, the checked rows are getting shifted randomly with in the sections.
The issue is that it's not there when I remove one section in the tableview. I.e even number of sections.
Can anyone help me?
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *kCustomCellID = #"MyCellID";
CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:kCustomCellID];
if (cell == nil)
{
cell = (CustomCell *) [[[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kCustomCellID]autorelease];
}
That is the code that I used.
I'm sure somewhere I did a mistake. But, I'm not able to find it.
this is because of reusing of cells in the table, read more about table reusing methodology.
To go in detail the changes made to a cell will be copied to others since the cells are reused to viewable cells.
We will need to see some code to properly diagnose the problem, specifically the implementation of - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {.
Are you correctly reusing the cells as specified in apples docs i.e.
static NSString *cellIdentifier = #"MyAwsomeCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier] autorelease];
}
Related
I have a table with a few rows, and the place holder text for all is the same. How can I programmatically change the placeholder text of only the first one?
Thanks!
You need to run an if statement to check the index of the cell. 0 is the first index, so you would need to check to see if the row is 0.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
if (indexPath.row == 0)
cell.textLabel.text = #"First Cell";
else
cell.textLabel.text = #"Not First Cell";
}
In order to access your cell AFTER the cell was created/reused, try the - (UITableViewCell *)cellForRowAtIndexPath:(NSIndexPath *)indexPath method of your uitableview object! See the following Apple doc for a detailed elaboration on this method.
Note:
Return Value
An object representing a cell of the table or nil if the cell is not
visible or indexPath is out of range.
In my tableview have custom cells that I initialize from a UITableViewCell class. I have sections for first letters of records and have an indexPath that is being created dynamically.
I wanted to add a search display controller to my tableview. So I did, created all methods to filter data. I am sure that my functions are working well because I am printing array count to screen for search results.
My problem is that the first time view loads, the data is on the screen. But when I hit the search input and type a letter, than I get 'UITableView dataSource must return a cell from tableView:cellForRowAtIndexPath:' error. After I used a breakpoint I saw that my custom cell is nil after searching. Data is exist, but cell is not being initialized.
Here is the code I use for custom cell initializing:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"ObjectCell";
SpeakerCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
NSDictionary *myObject = [[sections valueForKey:[[[sections allKeys] sortedArrayUsingSelector:#selector(localizedCaseInsensitiveCompare:)] objectAtIndex:indexPath.section]] objectAtIndex:indexPath.row];
cell.label1.text = [myObject objectForKey:#"myValue"];
return cell;
}
I believe I made a mistake when putting controls in IB. So I added screenshots of objects:
Connections inspector for my table view
Connections inspector for my search display controller
EDIT: Problem is actually solved, I have used a UISearchBar instead of Search Display Controller but I guess this issue remains unsolved. So I'm willing to try any ways to make it work.
As of here search display controller question,
you need to access the self.tableView instead of tableView:
-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:#"CellId"];
// do your thing
return cell;
}
For those using iOS 5 and StoryBoards, you would want to use the following method instead of initWithIdentifier:
initWithStyle:(UITableViewCellStyle)stylereuseIdentifier:(NSString *)reuseIdentifier
Example:
NSString *cellIdentifier = #"ListItemCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
I'm not sure about how this should work in storeboarding.
But normally you would check if the [tableView dequeueReusableCellWithIdentifier:CellIdentifier] returns a cell.
Because if the cell in not loaded before or there aren't any cells to reuse you will have to create a new cell:
SpeakerCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[SpeakerCell alloc] initWithIdentifier: CellIdentifier];
}
Also when in declaring local variables in Objective-C we tent not to capitalize the first letter.
I had the same issue, with custom cells (built in Storyboard) not being drawn as soon as the first letter was put in the search field. The search was successful however.
Finally I found a good tutorial from Brenna Blackwell suggesting to configure manually the cell drawing in the corresponding subclass of UITableViewCell, adding UILabels and other items.
i have a tableview that contains a uiwebview in its first row. i would like to change this tables' webview object with new one when user clicks a button. i am using the code given below but it does not work fine. older object is there and the newer one is over it although i recreate the webview. how can i remove the older one from cell?
thanks...
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
NSLog(#"NİL.......");
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
} else {
NSLog(#"NOT NİL.......");
}
[cell addSubview:webView];
return cell;
}
Since you are using "dequeueReusableCellWithIdentifier", your should reconfigure the cell each time when the cell is displayed.
Please remember that the cells with same identity will be reused. It's better to set the same identity to one particular type of cells, typically cells with same subviews and layout.
This is sample for how to load data and reconfigure a cell: http://code.google.com/p/tweetero/source/browse/trunk/Classes/MessageListController.m
Here is a tutorial to get familiar with UITableView:
http://developer.apple.com/library/ios/#documentation/userexperience/conceptual/TableView_iPhone/CreateConfigureTableView/CreateConfigureTableView.html
I need help in using checkbox cell. I currently added the object to tableview. It looks ok until i tried building and running the program where I cannot check the checkbox. I am currently using a tableview which displays items runtime with a checkbox for each item so i can have multiple selections.
I am new to xcode and I have been stuck for a week with this problem. i tried google but still no luck.
Any snippets, answers, or explanations is very much appreciated.
First we need to edit this method: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath. Assuming you generated a Navigation-based application, this method should already be there, only commented out. I don't know the exact details of your implementation, but you somehow have to keep track of the checkbox state for each cell in the tableView. For example, if you had a BOOL array, the following code would work:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
if (checkboxArray[indexPath.row])
checkboxArray[indexPath.row] = NO;
else
checkboxArray[indexPath.row] = YES;
[self.tableView reloadData];
}
Now that we know what cells need to have a checkmark next to them, the next step is to modify how the cell is displayed. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath handles the drawing of each cell. Building off the previous example, this is how you would display the checkbox:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
if (checkboxArray[indexPath.row]) {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
else
cell.accessoryType = UITableViewCellAccessoryNone;
// Configure the cell.
return cell;
}
If we don't call reloadData, the checkmark will not show up until it goes off-screen and reappears. You need to explicitly set the accessoryType each time because of the way cells are reused. If you set the style only when a cell is checked, other cells that may not necessarily be checked will have a checkmark when you go to scroll. Hopefully this gives you a general idea on how to use checkmarks.
I want to make a table view in my iPhone Application.. In that table each shall contains 1 image, some text of line, some symbols, etc.. I don't now how to customize our cell of table. Please provide some help if you have..
I think you can use a default UITableViewCell to do what you described by initializing the Cell (in - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath ) with the proper UITableViewCellStyle
e.g.:
-(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];
}
// Set up the cell...
return cell;
}
which gives you:
"A style for a cell with a left-aligned label across the top and a left-aligned label below it in smaller gray text. The iPod application uses cells in this style."
Also every kind of UITableViewCell has an image-property by default.
but here are some tutorials for building custom cells:
Custom UITableViewCells with Interface Builder
http://iphone.zcentric.com/2008/08/05/custom-uitableviewcell/
You can create a cell in Interface Builder. Start with a UITableViewCell which acts like a view, and then add a UIImage, one or more labels, whatever containers to hold your symbols, etc.
Then in your cellForRowAtIndexPath, load the nib and fill in the picture and labels, etc.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
MyTableCell *cell = (MyTableCell *) [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = myTableCell; // get the object from the outlet
myTableCell = nil; // make sure this can't be re-used accidentally
}
// Set up the cell...
cell.myViewController = self;
// set up image and labels here
return cell;
}