I got a prototype table with a custom Cell and inside this cell a textField.
My array of cells is a large one, so when I scroll the table, the cells need to be recreated.
Testing, when I scroll the text that was in the txt field of 1 cell goes to another, keyboard types change and everything gets messed-up!
CODE:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"customTableCell";
customTableViewCell *cell = (customTableViewCell*)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil)
{
cell = [[customTableViewCell alloc]
initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:nil];
}
// Configuration
cell.lblName.text = [self.pfFields objectAtIndex: [indexPath row]];
cell.txtType = [self.pfTypes objectAtIndex: [indexPath row]];
cell.mySql = [self.pfSql objectAtIndex: [indexPath row]];
//cell.txtField.delegate = self;
if ([[self.pfTypes objectAtIndex:[indexPath row]] isEqualToString: #"n"]) {
[cell.txtField setKeyboardType:UIKeyboardTypeNumberPad];
} else if ([[self.pfTypes objectAtIndex:[indexPath row]] isEqualToString: #"m"]) {
[cell.txtField setKeyboardType:UIKeyboardTypeEmailAddress];
}
return cell;
}
You need to be sure to set all properties of a cell in tableView:cellForRowAtIndexPath:, because a given cell can be reused at any time by the controller.
To prevent the text from jumping around, you need to set cell.txtField.text to the appropriate NSString loaded from your cell's backing object. Similarly, you should always set the keyboardType every time (I assume that there are cases besides just n and m). Setting the properties every time ensures that you get the correct display regardless of how the reused cell was previously configured.
Related
I was tasked to solve this bug in the app (It's for comercial use so I can't link the project). I'm also completely new to Objective-C or IOS development and I have no idea why the following happens. Reminder, I'm using custom cells.
When the tableview loads, everything looks fine.
Click here to see the example
But when I scroll up and back to the same postion the cell becomes blank, as if it had no data. Blank cell
If I repeat the same process everything looks fine again.
Here's the code for cellForRowAtIndexPath:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
static NSString *cellId = #"cell2";
PedTableCell *cell = [tableView dequeueReusableCellWithIdentifier:cellId];
if (cell == nil)
{
cell = [(PedTableCell*)[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellId];
}
if (tableView==_table3)
{
NSString *docsDirr;
NSString *documentsDirectoryForSaveImages;
docsDirr = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0];
documentsDirectoryForSaveImages = [docsDirr stringByAppendingPathComponent:#"/CarpetaImatges"];
NSString *match = #".jpg";
NSString *preCodigo;
NSScanner *scanner = [NSScanner scannerWithString:[pedarray objectAtIndex:indexPath.row]];
[scanner scanUpToString:match intoString:&preCodigo];
NSString *nomimg=[NSString stringWithFormat:#"%#.jpg", preCodigo];
UIImage *img = [UIImage imageWithContentsOfFile:[documentsDirectoryForSaveImages stringByAppendingPathComponent:nomimg]];
cell.img.image = img;
cell.layer.borderWidth=1.0f;
cell.img.layer.borderWidth=1.0f;
cell.cart.text = preCodigo;
cell.descart.text = [nomarray objectAtIndex:indexPath.row];
cell.cant.text = [cantarray objectAtIndex:indexPath.row];
cell.precart.text = [precioarray objectAtIndex:indexPath.row];
cell.pvpcart.text = [pvparray objectAtIndex:indexPath.row];
[cell layoutIfNeeded];
}
return cell;
}
I've debugged the method and everytime it returns a valid cell. When I click the empty cell it still works as expected. Essentially, the data is there, it's just not rendered for some reason.
I've checked other posts with the same/similar issue but nothing seems to really match. PrepareForReuse is a no go since there's no UI to be changed, just content. I'm getting the values of the arrays with indexPath.row to make sure I'm fetching the correct value. I've even tried to set the heightForRowAtIndexPath to the same height the cell should have (all cells are of the same size and never change) or let AutoLayout handle it but to no avail.
Code of numberOfRowsInSection (Returns the amount of orders that exists in database currently):
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
if(tableView == _table3)
{
[self cargacarro];
return pedarray.count;
}
return pedarray.count;
}
Any ideas?
Register your cell nib in storyboard or in code before tableview is loaded, and after replace dequeueReusableCell... with this one
PedTableCell *cell = [tableView dequeueReusableCellWithIdentifier:cellId forIndexPath:indexPath];
cell.img...
cell.cart...
remove this part, is no longer needed
if (cell == nil)
{
cell = [(PedTableCell*)[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellId];
}
I have a UITextField in a custom cell. Once I entered the value in first and second cells and when I scroll the UITableView textfield index are changing (first cell value changing to last cell). Can any one help me to resolve my issue?
Here is my code:
static NSString *cellIdentifier = #"TableCellID";
CustomTableViewCell *cell = (CustomTableViewCell *) [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil) {
cell = [[CustomTableViewCell alloc] init]; // or your custom initialization
}
cell.accessoryType = UITableViewCellAccessoryNone;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.txt_TCelltext.tag=indexPath.row;
cell.txt_TCelltext.placeholder=#"0.00";
[cell.txt_TCelltext setDelegate:self];
It is because of cell reuse. Try to populate the UITextField data from a dictionary (or) array. Try this:
- (UITableViewCell *)tableView:(UITableView *)tableViewLocal
cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
// Your Code
UITextField *textField = [[UITextField alloc]init];
textField.delegate = self;
textField.tag = indexPath.row;
if ([myTextFieldDictionary objectForKey:[NSString stringWithFormat:#"%ld", (long)textField.tag]])
{
textField.text = [[myTextFieldDictionary objectForKey:[NSString stringWithFormat:#"%ld", (long)textField.tag]];
}
}
-(void)textFieldDidEndEditing:(UITextField *)textField
{
[myTextFieldDictionary setValue:textField.text
forKey:[NSString stringWithFormat:#"%ld", (long)textField.tag]];
}
You can write below code in Viewdidload and cell for row at index path.
arrCells = [NSMutableArray new];
for (int i = 0; i < [[dic_demo objectForKey:#"Demo"] count]; i++) {
NSArray *objects = [[NSBundle mainBundle] loadNibNamed:#"CustomTableViewCell" owner:self options:nil];
CustomTableViewCell *cell = [objects objectAtIndex:0];
[arrCells addObject:cell];
}-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
CustomTableViewCell *cell = [arrCells objectAtIndex:indexPath.row];
}
Hope this will help you
static NSString *cellIdentifier = #"TableCellID";
in place of this line
use NSString *cellIdentifier = [NSString stringWithFormat:#"Cell_%d_%d", indexPath.section, indexPath.row];
If the cell is newly created, you assign a placeholder/ text to text filed. But if the same cell is reused and incase for the reused cell you didn't assign the placeholder/ text to the textfield from the data source of the current index path than the text filed will show the data for previous index path at which the cell was newly created. So to resolve your issue you need to assign the text to the text field based on the text for the current index path irrespective of the cell is newly created or reused.
To resolve this issue you have two options-
1) update the content of reusable cells text field with the data of the text field for current index path
2) in case of reusable cell release previous text field and create a new one, initialize with the data for the present row.
The 2nd approach involves some overhead, so I would suggest you to resolve your issue with 1st approach.
Sample code using 1st approach-
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell" forIndexPath:indexPath];
cell.backgroundColor=[UIColor clearColor];
UITextField *textField = nil;
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:#"cell"];
}
// assign placeholder text to text field
[cell.textFiled setPlaceholder:[textFiledTextsArray objectAtIndex:indexPath.row]];
return cell;
}
Sample code using 2nd approach-
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell" forIndexPath:indexPath];
cell.backgroundColor=[UIColor clearColor];
UITextField *textField = nil;
if (cell == nil)
{
cell = [[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:#"cell"];
}
textField = [[cell contentView] viewWithTag:indexPath.row];
if(textField ! = nil)
[textField removeFRomSuperView];
textField = [[UITextField alloc] initWithFrame:CGRectZero];
// customize text filed
// assign placeholder text to text field
[textFiled setPlaceholder:[textFiledTextsArray objectAtIndex:indexPath.row]];
[textField setTag:indexPath.row]; // set tag on text field
[[cell contentView] addSubview:textField];
[textField release];
return cell;
}
Note: The above sample code is just a rough idea, please use the above source/ customize it as per your requirements.
Place a breakPoint in the function below and you can see it gets called each time a cell becomes visible and hence your code inside that function resets the text in the textField. If something has struck you, don't wait! you can solve it with your own code.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
I am using UITextField, and every row have a CellLable and TextField. Lable and TextField data comes from array. While running the app, all data are comes fine but when scrolling the Tableview, Last 2-3 Rows unorganized.
NSMutableArray
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
ArrFieldData= [NSMutableArray arrayWithObjects:#"Fist Name", #"Last Name",#"User Name", #"Password",#"Confirm Password", #"Gender",#"DOB", #"Profile Pic",#"Deparment", #"Joining Date",#"Education", #"Role", nil];
Now cellForRowAtIndexPath Function
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
UITextField *txtField ;
if (cell ==nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
txtField = [[UITextField alloc]initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/3 + 40, 2, [UIScreen mainScreen].bounds.size.width/2, cell.layer.frame.size.height -5)];
[self setUpCell:cell withIndexPath:indexPath withTextField:txtField];
}
[self UpdateCell:cell withIndexPath:indexPath withTextField:txtField];
return cell;
}
SetUp Cell Function
-(void)setUpCell:(UITableViewCell *)cell withIndexPath:(NSIndexPath *)indexPath withTextField: (UITextField *)txtField {
cell.textLabel.text = [ArrFieldData objectAtIndex:indexPath.row];
cell.textLabel.font = [UIFont systemFontOfSize:12.0];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
txtField.tag = indexPath.row+1;
txtField.layer.borderColor = [UIColor grayColor].CGColor;
txtField.delegate = self;
txtField.layer.borderWidth = 1.0f;
txtField.layer.cornerRadius = 4.0f;
txtField.placeholder = cell.textLabel.text;
txtField.font = [UIFont systemFontOfSize:12.0];
[cell.contentView addSubview: txtField];
}
Update Cell Function
-(void)UpdateCell:(UITableViewCell *)cell withIndexPath:(NSIndexPath *)indexPath withTextField: (UITextField *)txtField {
[self setUpCell:cell withIndexPath:indexPath withTextField:txtField];
}
First time Running the application, It is showing all cell and textfield data are Serialize. but when scroll some cell and TextField are not serialize as per Array Value. I am attaching the Simulator Screenshot.
First Screenshot for First time running, and second for when i scroll the Tableview. See the last 4-5 cell and Textfield Placeholder text. They are un-organized. I want it shouldn't change.
As you are using reusable cells, like
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
UITextField *txtField ;
if (cell ==nil)
{
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
txtField = [[UITextField alloc]initWithFrame:CGRectMake([UIScreen mainScreen].bounds.size.width/3 + 40, 2, [UIScreen mainScreen].bounds.size.width/2, cell.layer.frame.size.height -5)];
[self setUpCell:cell withIndexPath:indexPath withTextField:txtField];
}
[self UpdateCell:cell withIndexPath:indexPath withTextField:txtField];
return cell;
}
UITableView uses the concept of reusable cell to achieve maximum performance by reducing the memory consumption, and to exploit this feature of reusing cells you can use the above UITableView's API's to achieve that.
But before using any feature it's very important to understand the working and the usage of any feature.
In your above implementation of tableView: cellForRowAtIndexPath: method, you have used the concept of cell reusability.
If the cells doesn't exist and are created for the first time, than they are allocated(every subview is created and added on the content view of the cell), customized and initialized with the data from the data source of the respective index path.
But in case the cells are reused(as they were already created for any other index path), there subviews exist with the data already filled for the previous index path for which it was created.
Now there are two things we can do to use already created cell for the current index path,
1) if the cells contain subview with data then remove the subviews and recreate the new ones, customize and populate them with the data.
2) rather than releasing the previous subviews and creating new ones, refill the data for the data model of the corresponding index path.
In your case, if the cell is being created for any index path, than the text filed for it is also created and if it's reused than the new text field is not created and it's being reused from the previously created cell thus the issue of the placeholder text not matching with the left text.
So, in order to solve your problem I think you should either create the textfield when the cell is created and if the cells are reused than refill the data in the text filed from the data source of the corresponding index path.
Your problem is due to a feature of UITableView. When you scroll a UITableView the indexPath is updated so you are not getting the index values you are expecting from the tableView.
Instead of adding a UITextField programmatically. Create a Custom UITableViewCell and from the method cellForRowAtIndexPath: update the placeHolder of your UITextField. The tableView will take care of scrolling for you.
Use this code :
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"cell"];
UITextField *txtField ;
if (cell ==nil) {
cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
cell.textField.placeholder= cell.textLabel.text;
}
cell.textField.placeholder= cell.textLabel.text;
return cell;
}
I'm trying to build an UITableView with some long texts inside each cell. Cells are without AccessoryView, except for one cell (the 8th one), that is a sort of button to open a detail view.
Consider this code:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
CGSize size = [[quotes objectAtIndex:indexPath.row] sizeWithFont:16 constrainedToSize:CGSizeMake(self.view.frame.size.width, CGFLOAT_MAX)];
return size.height+20;
}
- (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];
}
cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
cell.textLabel.numberOfLines = 0;
cell.textLabel.text = [quotes objectAtIndex:indexPath.row];
if(indexPath.row==7){
[cell setAccessoryType:UITableViewCellAccessoryDetailDisclosureButton];
}
return cell;
}
It works, but the problem is that when I scroll to the bottom of the Table (the 8th is also the last row) and then I go back to the upper side, another AccessoryView is added to a random point (more or less the 3rd cell, but I don't know if it is inside of it or is floating around randomly).
Is it something related to cell reusing by iOS? How can I avoid it?
Thanks in advance.
You have to explicitly set no disclosure button to every cell but the one that you wish to have disclosure. This way when the cell gets reused elsewhere its disclosure indicator is removed:
if(indexPath.row==7){
[cell setAccessoryType:UITableViewCellAccessoryDetailDisclosureButton];
}else{
[cell setAccessoryType:UITableViewCellAccessoryNone];
}
The cell is being reused (as demonstrated by your call to -dequeueReusableCellWithIdentifer).
The answer is to set the cell to wanted defaults after it's been dequeued, or add an else clause to the if statement to handle it.
- (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];
}
cell.textLabel.lineBreakMode = UILineBreakModeWordWrap;
cell.textLabel.numberOfLines = 0;
cell.textLabel.text = [quotes objectAtIndex:indexPath.row];
// Set to expected default
[cell setAccessoryType:UITableViewCellAccessoryNone];
if(indexPath.row==7){
[cell setAccessoryType:UITableViewCellAccessoryDetailDisclosureButton];
}
return cell;
}
This is due to cell reuse as you surmise. You must explicitly set UITableViewCellAccessoryNone for cells at index paths other than 7.
I am an iOS newbie. I am using a checkmark to in a UITableView, and storing the checked value in a local database. When I load the app for the first time, I want to set the value of the checkmark depending on which value exists in the db. How would I do that? Presently this is what I do -
- (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];
}
if ([indexPath compare:self.lastIndexPath] == NSOrderedSame)
{
cell.accessoryType = UITableViewCellAccessoryCheckmark;
}
else
{
cell.accessoryType = UITableViewCellAccessoryNone;
}
// Set up the cell...
NSString *cellValue = [[self countryNames] objectAtIndex:indexPath.row];
cell.textLabel.text = cellValue;
return cell;
}
and then in didSelectRowAtIndexPath -
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
// some stuff
self.lastIndexPath = indexPath;
[tableView reloadData];
}
Are you asking simply how and when to set the checkmark or are you asking how to populate a table from a database (eg Core Data)?
From your code, the only data you represent is in [self countryNames] and it's not clear under what circumstances you'd want the cell to display a checkmark. Whatever that is, just check the condition and set the checkmark when you are configuring your cell for data (after your "Set up the cell..." comment).
Example if you stored the users country and checked that cell:
// get the current country name
NSString *cellValue = [[self countryNames] objectAtIndex:indexPath.row];
// configure the cell
cell.textLLabel.text = cellValue;
UITableViewCellAccessoryType accessory = UITableViewCellAccessoryNone;
if ([cellValue isEqualToString:self.usersCountry]) {
accessory = UITableViewCellAccessoryCheckmark;
}
cell.accessoryType = accessory;
If you have static table data, then you simply need to store the section and row of the selected table view cell. If you have dynamic data, then you will need to store the unique data for that selected cell in the database and compare that with the cell's content on load. When you are loading your cells in cellForRowAtIndexPath:, simply set that cell's accessory to UITableViewCellAccessoryCheckmark as well as set self.lastIndexPath = indexPath for comparison later.
Also, I typically use [indexPath isEqual:self.lastIndexPath] instead of compare:. Doesn't really make a difference either way, just for readability.