I have created a TableView in my application with 5 sections in it.
Sections 1 - 4 only contain one row each for the minute and section 5 contains 5 rows.
Everything works fine until I scroll the TableView off the screen. In my first section and row (cell) I have the accessoryView set to a UILabel with some text in it.
Every other cell has the disclosure button as the accessoryType.
When I scroll the tableView the text I have in the first cell somehow appears in the the last cell!?
I have set up my data by adding NSStrings to array's and then adding them as dictionaries to an NSMutableArray.
And here is my cell set up:
- (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];
}
// UISwitch *aUISwitch = [[[UISwitch alloc]initWithFrame:CGRectZero]autorelease];
// Configure the cell.
NSDictionary *dictionary = [listOfSettings objectAtIndex:indexPath.section];
NSArray *array = [dictionary objectForKey:#"Settings"];
NSString *cellValue = [array objectAtIndex:indexPath.row];
cell.textLabel.text = cellValue;
if([cellValue isEqualToString:#"Status"]){
UILabel *viewLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 100, 20)];
[viewLabel setText:#"Connected"];
cell.accessoryView = viewLabel;
[viewLabel release];
}
else{
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
}
return cell;
}
I know cells get deleted/removed when they go off screen so I presume this has something to do with it? What is the recommended practice for dealing with cells that go off screen and reappear?
just at quick glance... in the else statement, not only do you need to set the cell.accessoryType, but also set the cell.accessoryView=nil;
the accesoryView is still there as the cell was recycled.
Related
I am creating a table with three different types of custom cell, One of them, one custom cell is having UITextField. I create two rows using this custom cell. I set tag and delegate for textfields of both row.
My problem is, when I scroll the table, these rows with textfields move up and disappear from the screen, when scroll down, that time my app gets crash.
I get an error like
-[CellImageViewController txtField]: unrecognized selector sent to instance 0xa0ea5e0
Here is my code for cellForRowAtIndexPath:
if (indexPath.row == 0 )
{
if (cell == nil) {
cell = [[[CellWithTextFieldViewController alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID] autorelease];
}
cell.txtField.tag =1;
cell.txtField.delegate = self;
cell.txtField.text = #"kjfkd";
}
return cell;
}
else if(indexPath.row==1)
{
if (cell == nil) {
cell = [[[CellWithTextFieldViewController alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellID] autorelease];
}
cell.txtField.tag = 2;
cell.txtField.text = #"glk";
cell.txtField.delegate = self;
return cell;
}
Any one have idea about this issue?
you have different type of cells, so you need to use a cellIdentifier different for each one.
Try this:
customOrNormalCell *cell [tableView dequeueReusableCellWithIdentifier:CellIdentifier]
if(!cell){
cell = [[CellWithTextFieldViewController alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:[NSString stringWithFormat:#"%i", indexPath.row]];
}
With this code, each cellIdentifier will be 1,2,3,4... (All different)
I'm pretty sure that it will solves the problem
create UITextField before create UITableView and Add your Textfield object in cell Content view
[cell.contentView addSubview:yourTxtFieldOblect];
It looks like you might be reusing a cell of a different type.
Try making sure which kind of class the cell you are reusing is before trying to access it's properties.
why you are define cell for each row?
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *CellIdentifier = [NSString stringWithFormat:#"Cell%d",indexPath.row];
CellWithTextFieldViewController *cell = (CellWithTextFieldViewController *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil)
{
cell =[[[CellWithTextFieldViewController alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier]autorelease];
cell.txtField.tag = indexPath.row;
cell.txtField.text = [SET TEXT FROM ARRAY];
cell.txtField.delegate = self;
}
}
I had also faced this problem in my project.
just try this:
Disabled the scrolling property in Tableview and create a scrollview.Then add your Tableview in your scrollview.
UITableView *table=[[UITableView alloc]initWithFrame:CGRectMake(0, 0, 976, 395) style:UITableViewStylePlain];
[table setSeparatorStyle:UITableViewCellSelectionStyleNone];
UIScroll *scroll=[[UIScrollView alloc]initWithFrame:CGRectMake(24, 168, 978, 395)];
[table setScrollEnabled:NO];
[scroll addSubview:table];
[self.view addSubview:scroll];
[scroll sendSubviewToBack:table];
Try this
static NSString *cellIdentifier= #"Cell";
CellWithTextFieldViewController *cell = (CellWithTextFieldViewController *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil) {
cell = [[CellWithTextFieldViewController alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
cell.txtField.tag =indexPath.row+1;
cell.txtField.delegate = self;
cell.txtField.text = #"kjfkd";
return cell;
While scrolling tableView your cell is getting reused. Thats why textField is disappearing. Try to use different cell id for different custom cells. Dont forget to give the same id in nib file for cell identifier
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *customCellOne = #"customCell1";
static NSString *customCellTwo = #"customCell2";
UITableViewCell *cell =nil;
if (0 == indexPath.row)
{
cell = (CustomCellOne *)[tableView dequeueReusableCellWithIdentifier:customCellOne];
if (nil == cell)
{
// Create custom cell one and do what ever you want
}
}
else if (1 == indexPath.row)
{
cell=(CustomCellTwo *)[tableView dequeueReusableCellWithIdentifier:customCellTwo];
if (nil == cell)
{
// Create custom cell two and do what ever you want
}
}
return cell;
}
I don't know,may be when reused the cell,the textfield delegate was released.
may be you can set the
textfield.deleagate = self;
in CellWithTextFieldViewController.m
I created UIScrollview with in UITableViewCell. The scrollView has some pictures to display in horizontally. It works good in one row but I am loading more than one row cells, it makes an issue when one cell is replaced by other cells.
I am using [tableView dequeueReusableCellWithIdentifier:section].
I also gave separate identifier for each row.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *section = [NSString stringWithFormat:#"section%#cell", indexPath.section];
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:section];
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithStyle: UITableViewCellStyleDefault reuseIdentifier:section];
NSArray *pageImages = imgs;
}
else
{
NSLog(#"recall");
}
return cell;
}
You don't want to give each cell a different reuse identifier. Change
NSString *section = [NSString stringWithFormat:#"section%#cell", indexPath.section];
to
NSString *section = #"Arbitrary";
Below is code for UITableView, But when i scroll its behaves weirdly (too annoying)... This problem is due to reuseIdentifier.... but dont know how to solve..
- (UITableViewCell *)tableView:(UITableView *)tableView1 cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView1 dequeueReusableCellWithIdentifier:CellIdentifier];
NSInteger imgTag = 1;
NSInteger lblTag = 2;
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(2, 2, 52, 52)];
// Image:[UIImage imageNamed:[self.glassType objectAtIndex:indexPath.row]]];
imgView.tag = imgTag;
[cell.contentView addSubview:imgView];
[imgView release];
UILabel *lblName = [[UILabel alloc] initWithFrame:CGRectMake(60, cell.frame.size.height/4, 200, 21)];
// lblName.text = [self.glassName objectAtIndex:indexPath.row];
lblName.tag = lblTag;
[cell addSubview:lblName];
[lblName release];
}
NSInteger imgIndex = 2;
NSInteger lblIndex = 3;
((UIImageView *)[cell viewWithTag:imgTag]).image = [[self.glassType objectAtIndex:indexPath.row] objectAtIndex:imgIndex];
((UILabel *)[cell viewWithTag:lblTag]).text = [[self.glassName objectAtIndex:indexPath.row] objectAtIndex:lblIndex];
return cell;
}
- (void)tableView:(UITableView *)tableView1 didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView1 cellForRowAtIndexPath:indexPath];
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
How to make Cell for row at index so that it remains constant even when scrolled??? Also how to make single selection in UITableView??
The answer is that you should not add subviews to your table cells outside of the "if (cell == nil) { ..." clause or they get added over and over again to the same cell when it gets re-used.
See my answer to this question for a more detailed explanation, including code for how to fix it:
cellForRowAtIndexPath memory management
You also cannot store state in table cells because as soon as they scroll offscreen they are recycled and re-appear at a different index in your table. You need to set up an array of model objects to store state for your table cells (such as what their accessory type should be). A more detailed explanation can be found in my answer to this question:
Looping through UITableViewCells of a UITableView
If you fix how you are adding subviews to the cells, and store your "ticked" state in an array of model objects as well as setting the cell.accessoryType (so that it can be restored when the cell is dequeued), then your approach to row selection is otherwise correct.
So put this in your tableView:cellForRowAtIndexPath: method, just before the return cell;:
MyModelObject *object = [self.arrayOfModelObjects objectAtIndex:indexPath.row];
BOOL isChecked = object.checked;
cell.accessoryType = isChecked? UITableViewCellAccessoryCheckmark: UITableViewCellAccessoryNone;
And in your tableView: didSelectRowAtIndexPath: method, get rid of the current logic and replace it with:
- (void)tableView:(UITableView *)tableView1 didSelectRowAtIndexPath:(NSIndexPath *)indexPath
for (int i = 0; i < [self.arrayOfModelObjects count]; i++)
{
MyModelObject *object = [self.arrayOfModelObjects objectAtIndex:i];
object.checked = (i == indexPath.row); // only check the one we just tapped
}
//refresh table to update the accessory views for all rows
[tableView1 reloadData];
}
Obviously replace the arrayOfModelObjects with your own model implementation. You could just use an array of NSNumber objects containing bools if you don't want to create a custom class for this purpose.
The recycling queue is like a pool where previously created Cells are stored before to reuse them. For example when you scrolls up, at the moment the cell disappears above, it is stored in the queue and becomes available for the cell that will appear at the bottom. Ok ?
Actually the number of cells really created is exactly the max simultaneous cell you can display in your table (in most cases from 3 to 8). In other words your if (cell == nil) code is executed (more or less from 3 to 8 times) at the first reloadData to create the pool of cells your table needs.
Then all you make on a cell is kept as it and appears again when you dequeue it. It's now easy to understand that, in your code, you have to make all strictly row-dependant settings outside the if (cell == nil) block. The same way, do not add subViews outside the if (cell == nil) block, you can imagine the thousands of subview you will add each time you reset a dequeued cell !
Tip: if you need some custom cleanup before reusing a cell (like to set an image to blank), you can create a custom UITableviewCell class and implements the prepareForReuse method.
Is it clear ?
Always reload your tableView in viewWillAppear method instead of viewDidLoad.
(void) viewWillAppear:(BOOL)animated{
[self.tableView reloadData];
}
This avoids most of all unexpected and annoying problems. :)
I have an tableview which is loaded from a mutablearray as listed below. However I need to asign each item in the array an ID and have a tickbox next to the item. Basically it's preferences for our search, it lets users prioritise by whichever tickboxes are ticked. So I'll want to save which items are ticked to a plist or similar.
Heres how the array is loaded:
arryTableIconsText = [[NSMutableArray alloc] init];
[arryTableIconsText addObject:#"Facilities for partially sighted or blind people"];
[arryTableIconsText addObject:#"An 'assistance dogs welcome' policy"];
[arryTableIconsText addObject:#"Disabled access facilities for wheelchair users (with assistance)"];
*more items added here*
arryTableIcons = [[NSMutableArray alloc] init];
[arryTableIcons addObject:#"visuallyImpaired_off.png"];
[arryTableIcons addObject:#"guidedogs_off.png"];
[arryTableIcons addObject:#"wheelchairassist_off.png"];
*more items added here*
And then loaded in to a table like so:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
}
cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
cell.textLabel.numberOfLines = 0;
cell.textLabel.font = [UIFont fontWithName:#"Helvetica" size:17.0];
cell.textLabel.text = [arryTableIconsText objectAtIndex:indexPath.row];
cell.imageView.image = [UIImage imageNamed:[arryTableIcons objectAtIndex:indexPath.row]];
return cell;
}
The result is the following:
But I don't know where to go from here to convert it in to a checkbox to the right of each cell with the ID saved?
Any tips really will be appreciated, Tom
Use an NSMutableIndexSet instance variable and populate it with the index of the cells being checked.
Then in the cellForRowAtIndexPath method, set the accessory type of the cell to UITableViewCellAccessoryTypeCheckmark or UITableViewCellAccessoryTypeNone depending on whereas the indexPath.row is in the NSMutableIndexSet or not.
Finally, when the cell is tapped, add the indexPath.row to the indexset if not alread, or remove it if it already was present, to toggle the status of the corresponding cell, then call reloadData on the tableView.
I see in your code too that you are not familiar with the reuse mechanism of UITableViewCells. You should read the "Table View Programming Guide" in Apple's documentation and learn how to implement cellForRowAtIndexPath in a more efficient and reactive way (in term of reactivity and memory footprint)
Example
// Let selectedCellIndexes be an instance variable in your .h of type NSMutableIndexSet*
// Initialize it (probably at the same place you initialise your texts & icons, once for all, probably in your init method
selectedCellIndexes = [[NSMutableIndexSet alloc] init];
Then to fill the cells:
-(UITableViewCell*)tableView:(UITableView*)tv cellForRowAtIndexPath:(NSIndexPath*)indexPath {
// Try to recycle and already allocated cell (but not used anymore so we can reuse it)
UITableViewCell* cell = [tv dequeueCellWithReuseIdentifier:...];
if (cell == nil) {
// If we didn't manage to get a reusable (existing) cell to recycle it
// then allocate a new one and configure its general properties common to all cells
cell = [[[UITableViewCell alloc] initWithStyle:... reuseIdentifier:...] autorelease];
// ... configure stuff that are common to all your cells : lineBreakMode, numberOfLines, font... once for all
cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
cell.textLabel.numberOfLines = 0;
cell.textLabel.font = [UIFont fontWithName:#"Helvetica" size:17.0];
}
// Then here change the stuff that are different between each cell
// (this code will be executed if the cell has just been allocated as well as if the cell is an old cell being recycled)
cell.textLabel.text = [arryTableIconsText objectAtIndex:indexPath.row];
cell.imageView.image = [UIImage imageNamed:[arryTableIcons objectAtIndex:indexPath.row]];
cell.accessoryType = [selectedCellIndexes containsIndex:indexPath.row] ? UITableViewCellAccessoryTypeCheckmark : UITableViewCellAccessoryTypeNone;
return cell;
}
And finally, to toggle the checkmarks:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
if ([selectedCellIndexes containsIndex:indexPath.row]) {
[selectedCellIndexes removeIndex:indexPath.row];
} else {
[selectedCellIndexes addIndex:indexPath.row];
}
[tableView reloadData];
}
as you see in the screen prints, tableView always displays a single value in the tableView "Title" My problem is to display all the array values detailTableView
- (void)viewDidLoad {
NSArray* tmpArray = [[NSArray alloc] initWithObjects:#"Titre", #"Nom", #"Prenon",#"Adresse",#"Phone",#"Mobile",#"Mail",#"Site",#"Note",nil];
self.detailsTableView = tmpArray;
[tmpArray release];
[super viewDidLoad];
}
- (UITableViewCell *)tableView:(UITableView *)atableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
// Configure the cell...
cell.textLabel.text =[self.detailsTableView objectAtIndex:indexPath.row] ;
return cell;
}
From the screen grab, it looks like you've only got one cell per section. In which case you need to use indexPath.section instead of indexPath.row.
From the apple Documentation
textLabel
Returns the label used for the main textual content of the table cell. (read-only)
#property(nonatomic, readonly, retain) UILabel *textLabel
Discussion
Holds the main label of the cell. UITableViewCell adds an appropriate label when you create the cell in a given cell style. See “Cell Styles” for descriptions of the main label in currently defined cell styles.
So Create a new UILabel and add it to textLabel
did you set as follows:
- (NSInteger)tableView:(UITableView *)aTableView numberOfRowsInSection:(NSInteger)section {
return [self.detailsTableView count];
}