UITableView cell/data disappear - iphone

Question

I have a segmented tableView that loads all the data in all the cells of all the sections.
There is a textField in each cell.
The tableview doesn't fit the iPad screen completely, and I can't access all the invisible cells in order to read/save data. And when I make changes in "textField", then scroll up, the scroll down, all the changes are gone.
I need to load all the cells, even invisible once, to be able to access them.
I am sorry, I just started working with tables a few days ago...
I think that this problem has something to do with reusable cells, but not sure how to resolve it.
Looking for your help, please.
initialization:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 400, 30)] ;
textField.enabled = NO;
cell.accessoryView = textField;
[textField release];
}
UITextField *textField = (UITextField*)cell.accessoryView;
if(indexPath.section == 0)
cell.textLabel.text = [idenInfo objectAtIndex:indexPath.row];
else if (indexPath.section == 1)
cell.textLabel.text = [prodInfo objectAtIndex:indexPath.row];
else if (indexPath.section == 2)
cell.textLabel.text = [visInfo objectAtIndex:indexPath.row];
if(indexPath.section == 0)
textField.text = [idenInfoRez objectAtIndex:indexPath.row];
else if (indexPath.section == 1)
textField.text = [prodInfoRez objectAtIndex:indexPath.row];
else if (indexPath.section == 2)
textField.text = [visInfoRez objectAtIndex:indexPath.row];
textField = nil;
return cell;
}

Answer 1

First of all : you don't have to load all the cells including the invisible ones. That's the whole point of the UITableView and MVC Pattern : separate your views from your data.
What you'll want to do is update your Data source (that is idenInfoRez, prodInfoRez and vizInfoRez in your case) when the user has changed a value inside a textField. So you'll have to set your UIViewController as the delegate of each textfield and update the values as the user types in.

Answer 2

[UIView beginAnimations:#"ShiftUp" context:nil];
[UIView setAnimationDuration:0.0001];
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSInteger section = [indexPath section];
static NSString *CellIdentifier = #"Cell";
CustomCell *cell = (CustomCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
[[NSBundle mainBundle] loadNibNamed:#"CustomCell" owner:self options:nil];
cell = objCustCell;
cell.selectionStyle = UITableViewCellSelectionStyleNone ;
}
if (section == 0) {
switch (indexPath.row) {
case 0:{
cell.lable.text = #"Date of Birth";
cell.field.placeholder = #"Birth Name";
break;
}
case 1:{
cell.lable.text = #"Enter Your Name";
cell.field.placeholder = #"Full Name";
break;
}
default:
break;
}
}
[UIView beginAnimations:#"ShiftUp" context:nil];
[UIView setAnimationDuration:0.0001];
// [UIView beginAnimations: #"ShiftUp" context:nil];
NSLog(#"Load cellfor raw at index ");
// Configure the cell.
return cell;
}
Note : UIView animation will not allow text field to move away data or any UIcontroller will remain same in its old state !!
Don't Commit animation otherwise it will not working !!

Answer 3

What you can do is this: in the Editing Changed event of each of the TextField store the value contain in the text field in an NSMutableArray whose number equal the number of cells. i.e.
-(IBAction) EditingChanged: (id) sender
{
UITextField *txt =(UITextField*)sender;
NSString* str =[[NSString alloc] initWithString: txt.text];
//get current text string
NSInteger path =[tableView indexPathForSelectedRow].row;
// get currently selected row, this could be a bit different depending on the number of sections
[yourMutableArray insertObject: str atIndex: path];
[str release]
}
You can then populate the TextField with the values from the NSMutableArray anytime the cells are recreated i.e.
(UITableViewCell *) tableView: (UITableView*)tableView cellForRowAtIndexPath:(NSIndexPath*) indexPath
{
...... // create the cells here and use viewTag to get the textFields
textField.text= [yourMutableArray objectAtIndex:indexPath.row];
//This may be a bit different depending on the number of sections.
}
Also, note that it might be advisable to initialize yourMutable array to the capacity of the number of cells.
I am sorry if the codes are not well formatted as this is my first post on stackoverflow - also there might be some typos in the code. Hope this helps someone.

Answer 4

every time we allocate the cell to different data,the data will not reloading the cell,every time the data override previous data, before allocate the cell to clear cell,
like as cell=nil
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
cell=nil;
//it clear data in the cell
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 400, 30)] ;
textField.enabled = NO;
cell.accessoryView = textField;
[textField release];
}

Answer 5

You're right, the problem is the cells will be reused. There are two solutions to the problem, the quick and dirty one would be to not use reusable cells:
Remove this:
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
And just leave this:
UITableViewCell * cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 400, 30)] ;
textField.enabled = NO;
cell.accessoryView = textField;
[textField release];
That should be ok, if you have only a small number of cells in your tableview (about fewer than 50).
The better solution would be to leave cell reuse on, and fill their textfields as they are requested. The approach differs from app to app, but you basically never should access the cells directly, and store the data of the cell somewhere else, e.g. an NSArray of NSStrings. You could then manipulate the NSArray. Your cellForRowAtIndexPath method would look something like this:
textField.text = [arrData objectAtIndex:indexPath.row];