Data lose On UITableViewCell When UITableView Scrolling? - iphone

Question

I am trying to implement UITableview based application. In my tableView their is 10 Section and each section having one row.
I want implement each section have Different type of ContentView(1-8 same ContentView 9th section Different ContentView). I did this code For that.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return 10;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return 1;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier1 = #"Cell1";
static NSString *CellIdentifier2 = #"Cell2";
UITextField *textField;
UITextView *textView;
NSUInteger section=[indexPath section];
if(section == 9){
UITableViewCell *cell=[self.tableView cellForRowAtIndexPath:indexPath];
//UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier1];
if(cell==nil){
cell=[[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier1]autorelease];
textView=[[UITextView alloc]initWithFrame:CGRectMake(5, 5, 290, 110)];
[textView setBackgroundColor:[UIColor scrollViewTexturedBackgroundColor
]];
[textView setTag:([indexPath section]+100)];
[cell.contentView addSubview:textView];
}else{
textView=(UITextView*)[cell.contentView viewWithTag:([indexPath section]+100)];
}
return cell;
}else {
UITableViewCell *cell=[self.tableView cellForRowAtIndexPath:indexPath];
// UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier2];
if(cell==nil){
cell=[[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier2]autorelease];
textField=[[UITextField alloc]initWithFrame:CGRectMake(5, 5, 290, 50)];
[textField setBackgroundColor:[UIColor scrollViewTexturedBackgroundColor]];
[textField setTag:([indexPath section]+100)];
[cell.contentView addSubview:textField];
}else{
textField=(UITextField*)[cell.contentView viewWithTag:([indexPath section]+100)];
}
return cell;
}
return nil;
}
My problem are:
1. After type some thing in the UITextField/UITextView i am scrolling in the UITableView. that time all data in the UITableViewCell(UITextField/UITextView) was lose, except last cell data.
2. If i create cell
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
Instead of
UITableViewCell *cell=[self.tableView cellForRowAtIndexPath:indexPath];
Data will repeating . How can i over come this problem?

Answer 1

This line:
UITableViewCell *cell=[self.tableView cellForRowAtIndexPath:indexPath];
Should never appear in your data source cellForRowAtIndexPath method.
Apart from that, your code is OK, except that you are not setting the text field value anywhere. You need a model (such as an array of strings for the 10 textfield values). This model should be updated when the textfields are edited, and in your method above you copy the value back out of the model and into the textfield's text property:
textfield.text = [self.modelArray objectAtIndex:indexPath.section];

Answer 2

The table pools and reuses cells in an unpredictable fashion, so that subview of a cell that just scrolled off the bottom might reappear next at the top, or might be disposed of.
This is why you saw it partially work. The cell's subviews work okay until their cell gets reused or unloaded, then things move to the wrong place or data disappears.
The solution is that your table's datasource needs to hold onto it's own data. This is usually an array representing your model. Your case is a little unusual because you are using the text controls in your table as inputs, rather than display, which is more typical.
I suggest doing it like this:
// in #interface
#property (nonatomic, retain) NSMutableArray *sections;
// in #implementation
#synthesize sections=_sections;
// at some point before the view appears
self.sections = [NSMutableArray array];
for (int i=0; i<10; i++) {
UIControl *textControl;
if (i<9) {
textControl=[[UITextView alloc]initWithFrame:CGRectMake(5, 5, 290, 110)];
} else {
textControl=[[UITextField alloc]initWithFrame:CGRectMake(5, 5, 290, 50)];
}
[textControl setBackgroundColor:[UIColor scrollViewTexturedBackgroundColor]];
[textControl setTag:i+100];
[sections addObject:textControl];
[textControl release];
}
Now your cellForRowAtIndexPath is a little simpler:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier1 = #"Cell1";
static NSString *CellIdentifier2 = #"Cell2";
NSUInteger section=[indexPath section];
if(section == 9) {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier1];
if(cell==nil) {
cell=[[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier1]autorelease];
}
} else {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier2];
if(cell==nil) {
cell = [[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier2]autorelease];
}
}
// who knows what subview this cell has? it might not have one, or it might have the wrong one
// just clean it up to be certain
for (UIView *view in cell.subviews) {
[view removeFromSuperView];
}
// get the textControl we set up for _this_ section/cell
UIControl *textControl = [self.sections objectAtIndex:section];
// now we have a fresh cell and the right textControl. drop it in
[cell addSubview:textControl];
return cell;
}

Answer 3

hey the reason is you are doing this things when cell is nil ? but you are not writing any code when cell is not nil.
look at this example , in this example i am adding image view in tableview cell , hence you can add textviews or any other views like this
UITableViewCell *cell = (UITableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
UIImageView *imgView;
if(cell == nil)
{
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
imgView = [[UIImageView alloc] initWithFrame:CGRectMake(100,0,100,62)];
[imgView setImage:[UIImage imageNamed:#"img.png"]];
imgView.tag = 55;
[cell.contentView addSubview:imgView];
[imgView release];
}
else
{
imgView = (id)[cell.contentView viewWithTag:55];
}
so as showin here imgView = (id)[cell.contentView viewWithTag:55]; you have to give tag to you and write code showing above in else..

Answer 4

Let you try to make the cell labels and textviews by using following code. It works for me.
if (tagvalue ==3) {
static NSString *CellIdentifier = #"Cell3";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
reuseIdentifier:CellIdentifier] autorelease];
}
lbl7 = [[UILabel alloc] init];
[lbl7 setFont:[UIFont boldSystemFontOfSize:20]];
[cell.contentView addSubview:lbl7];
lbl7.backgroundColor = [UIColor clearColor];
lbl7.frame = CGRectMake(120, 5, 0, 40);
lbl7.tag = 70;
[lbl7 release];
lbl8 = [[UILabel alloc] init];
[lbl8 setFont:[UIFont boldSystemFontOfSize:18]];
[cell.contentView addSubview:lbl8];
lbl8.backgroundColor = [UIColor clearColor];
lbl8.textColor = [UIColor grayColor];
lbl8.frame = CGRectMake(120, 50, 0, 40);
lbl8.tag = 80;
[lbl8 release];
lbl7 = (UILabel*)[cell.contentView viewWithTag:70];
lbl8 = (UILabel*)[cell.contentView viewWithTag:80];
lbl7.text = [[rowsarray objectAtIndex:row]objectForKey:#"name"];
lbl8.text = [[rowsarray objectAtIndex:row]objectForKey:#"flavour"];
[lbl7 sizeToFit];
[lbl8 sizeToFit];
return cell;
}
if (tagvalue ==4) {
static NSString *CellIdentifier = #"Cell4";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
}
lbl9 = [[UILabel alloc] init];
[lbl9 setFont:[UIFont boldSystemFontOfSize:20]];
[cell.contentView addSubview:lbl9];
lbl9.backgroundColor = [UIColor clearColor];
lbl9.frame = CGRectMake(120, 5, 0, 40);
lbl9.tag = 90;
[lbl9 release];
lbl10 = [[UILabel alloc] init];
[lbl10 setFont:[UIFont boldSystemFontOfSize:18]];
[cell.contentView addSubview:lbl10];
lbl10.backgroundColor = [UIColor clearColor];
lbl10.textColor = [UIColor grayColor];
lbl10.frame = CGRectMake(120, 50, 0, 40);
lbl10.tag = 100;
[lbl10 release];
lbl9 = (UILabel*)[cell.contentView viewWithTag:90];
lbl10 = (UILabel*)[cell.contentView viewWithTag:100];
lbl9.text = [[rowsarray objectAtIndex:row]objectForKey:#"name"];
lbl10.text = [[rowsarray objectAtIndex:row]objectForKey:#"flavour"];
[lbl9 sizeToFit];
[lbl10 sizeToFit];
return cell;
}

Answer 5

I had same issue. Its not the problem with table class. The issue is at the place where you are calling this tableviewcontroller. First make the object of this call in .h and then allocate in .m, thats it..
When I was declaring in viewdidload like tbl *t = [self.storyboard...];, I was also facing the same problem. But when I put tbl *t; in .h problem solved.