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.
Related
I am having a problem with the Settings page of my app. I have chosen to use static cells so I have a few table sections with 3-4 cells in each.
In viewDidLoad I load my NSUserDefaults and set the accessory marks like this:
...
}
else if ( ... my Condition3 ... ) {
indexPath = [NSIndexPath indexPathForRow:2 inSection:0];
}
UITableViewCell* cell = [settingsTable cellForRowAtIndexPath:indexPath];
cell.accessoryType = UITableViewCellAccessoryCheckmark;
This works fine and it sets the cell with the matching setting with a Checkmark. However, this is only working for the cells that are on screen by default. Any cells which require scrolling do not contain the checkmark.
Is there a way to fix this, preferably without having to use dynamic cells?
Ahh, I finally figured it out. cellForRowAtIndexPath crashes the app so I had to do the following:
I set the cells which require a checkmark in my viewDidAppear method using the code above (in the question). I also remove all checkmarks and then add one to the selected cell in the didSelectRowAtIndexPath method as I was doing before.
In each of the two methods I set an NSString variable to the .textview.text of the selected cell and then implement this method:
-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
cell.accessoryType = UITableViewCellAccessoryNone;
if ([cell.textLabel.text isEqualToString:[NSString stringWithFormat:#"%#", myFirstString]] || [cell.textLabel.text isEqualToString:[NSString stringWithFormat:#"%#", mySecondString]]) {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
}
Hopefully this might help someone.
That's because when you scroll your cells are rebuilt and the checkmarks are cleaned.
You need to set it up in the
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
I am working with grouped tableview with multiple sections.
and I have to implement the functionality of multiple selection on didselectrow at indexpath
method. my code is as follows.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)path
{
UITableViewCell *cell = [tableView cellForRowAtIndexPath:path];
if (cell.accessoryType == UITableViewCellAccessoryCheckmark)
{
cell.accessoryType = UITableViewCellAccessoryNone;
}
else
{
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
}
which allows me to select multiple cells
but when I scroll my tableview at that time my selection disappears.
Your selection goes off when you scroll because it calls cellForRowAtIndexPath and there you have not handle selection.
To avoid this problem you can do as follows:
In didSelectRowAtIndexPath you can save index path of selected row as follows:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)path
{
UITableViewCell *cell = [tableView cellForRowAtIndexPath:path];
if (cell.accessoryType == UITableViewCellAccessoryCheckmark)
{
cell.accessoryType = UITableViewCellAccessoryNone;
//remove index path
[selectedIndexPathArray removeObject:path];
}
else
{
cell.accessoryType = UITableViewCellAccessoryCheckmark;
[selectedIndexPathArray addObject:path];
}
}
and in cellForRowAtIndexPath you can check whether cell is selected or not.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//If selectedIndexPathArray contains current index path then display checkmark.
if([selectedIndexPathArray containsObject:indexPath])
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
Try this
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:nil];
if (self.tableView.isEditing) {
cell.selectionStyle = UITableViewCellSelectionStyleBlue;
} else {
cell.selectionStyle = UITableViewCellSelectionStyleNone;
}
return cell;
}
-(UITableViewCellEditingStyle) tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath {
return UITableViewCellEditingStyleMultiSelect;
}
-(IBAction) switchEditing {
[self.tableView setEditing:![self.tableView isEditing]];
[self.tableView reloadData]; // force reload to reset selection style
}
Hope this helps solving your problem.(ref)
Your selection disapear cause the method CellForRowAtIndexPath will be called at scroll.
You need to set the accessory again.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
...
// here
...
}
You are getting this issue because you are not tracking your row selections.When the callback method cellForRowAtIndexPath gets called for the rows that had disappeared/(scrolled up/down) the cell object no longer remembers whether it was selected or not. (reason those selections are disappearing)
I would suggest you to use a collection like NSMutableArray/NSArray to track the selected rows.
You can use either of these approaches.
This would be a quick working fix:
Add/Remove the index path object in didSelectRowAtIndexPath based on the users selection
and then based on the contents of that array u can toggle the value of cell.accessoryType for the corresponding cell.
Ideally,you can use a data bean/model with some boolean member called selected and u can update its value based on the selection made.Then instead of simply adding those index path u can add those meaningful data bean objects onto your array and get the selections back from the selected property of the bean.This approach would help u in getting back the row selections even if the user kills and restarts the app provided u persist the bean objects in database/archive..(But it all depends on ur use case and requirements!)
Hope this helped!
I made a UITableViewCell and I have 20 rows in that table in which 5 at a time on screen.
I have set accessory view checkd mark in didSelect delegate method on which row is being selected. My concern is let suppose first row is selected and its accessory type is checked, now if i scroll the table we see the sixth one is also checked. I know that the cell is reusing itself and not creating itself again.
The model should be able to handle which cell is checked and which is not. To simplify the problem, you can keep an array which will the NSIndexPaths that should be checked. If only one can be checked at the time, an ivar of the type NSIndexPath is more than enough.
- (void)tableView:(UITableView *)aTableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
if ([[aTableView cellForRowAtIndexPath:indexPath] accessoryType] == UITableViewCellAccessoryCheckmark)
{
// Ok this one is selected, so we will remove it from the Reference Array.
}
else
{
// Ok this one doesn't has a checkMark
// First add the checkmark
[[aTableView cellForRowAtIndexPath:indexPath] setAccessoryType:UITableViewCellAccessoryCheckmark];
// Add the NSIndexPath to the Array of references
}
}
In the delegate method
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
NSString *cellId = [NSString stringWithFormat:#"cell%d",indexPath.row];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellId ];
if (cell==nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1
reuseIdentifier:cellId ] autorelease];
}
}
Set different cell ID to different cell row.
I have got an iphone project that has a UITableView which is populated from Core Data..
When a cell is selected, the user is directed to a new view controller (see code line below) which shows additional information about that cell entry (from core data)
[self presentModalViewController:noteViewController animated:YES]
What i want to do is to be able to set some sort of checkmark on either side of each cell to represent whether the task is complete of incomplete..
I have read that i could do this using:
UITableViewCellAccessoryCheckmark
but i am not sure how to implement is as currently
didSelectRowAtIndexPath:
is being used to present the modal view controller..
So essentially i want to know if there is a method for changing the state of a cell's accessory from checkmark to nothing (and vice versa) independently.. in the sense that if the actual checkmark is touch.. it shows it.. and if it is touched again, it hides it..
Any help would be greatly appreciated!
You will need to track selected rows externally from Cell presentation. This means, your model (that you used to build the cells in the first place) will need to track some sort of boolean. Once you have that you set accessoryType to the proper type.
i.e.
if ([[data objectAtIndex:indexPath.row] isSelected]) {
cell.accessoryType = UITableViewCellAccessoryCheckmark;
} else {
cell.accessoryType = UITableViewCellAccessoryNone;
}
This would be some of the logic in your:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *selectedCell = [tableView cellForRowAtIndexPath:indexPath];
if (selectedCell.accessoryType == UITableViewCellAccessoryNone)
{
selectedCell.accessoryType = UITableViewCellAccessoryCheckmark;
}
else
if (selectedCell.accessoryType == UITableViewCellAccessoryCheckmark)
{
selectedCell.accessoryType = UITableViewCellAccessoryNone;
}
//Do something
}
Hope this helps
UPDATE
This tutorial will give you a basic info on custom table view cell.
Another Reference.
I think this will give you the solution.
Here is an xcode project that I just did to ask this question:
http://www.mediafire.com/?z26ufsfhby62br9
Open the log and run it. You will find that it outputs display: x and create: x where x is a number 0 to 49 and corresponds to the cell of the same number. It should only output to 22 before any scrolling is performed as Apple are always boasting that their tableviews are loaded as needed.
It basically shows that tableView:willDisplayCell:forRowAtIndexPath: and tableView:cellForRowAtIndexPath: are fired for each cell pretty much as soon as the tableview appears, why is this?
- (UITableViewCell *)tableView:(UITableView *)tableView
cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSLog(#"create: %i", indexPath.row);
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell...
cell.textLabel.text = [NSString stringWithFormat:#"%i", indexPath.row];
return cell;
}
- (void) tableView:(UITableView *)tableView
willDisplayCell:(UITableViewCell *)cell
forRowAtIndexPath:(NSIndexPath *)indexPath {
NSLog(#"display: %i", indexPath.row);
}
Why are the above meothds called just after the tableView loads (and just before each cell appears)? Surely they should be called just before each cell appears only?
These are the default delegate methods.. This will be be called for each cell everytime.
You use willDisplayCell:forRowAtIndexPath: to configure things like font and text color. In the newer version of the iPhone, with certain table configurations, if you configure things like the label text color in the tableView:cellForRowAtIndexPath: method, your changes will be lost at some point before the cell is actually displayed. Here you can do things like change the label's color, adjust background highlighting, such things as these.
If your table view is reloading before it actually fully displays, that could cause the behavior you're seeing. Then the cells would get initialized, prepared for display, but then all of that would be lost (before even shown on screen) as the table is reloaded.