UITableView Cell is regenerating - iphone

Question

I have UITableViewCell with UILabel and UISwitch. By default all UISwitch is set to off.
Once I will turn on the switch and then scroll through table the switch value is set to default again,i.e.Off
Below is the code which I have used:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell != nil) cell = nil;
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
if (indexPath.row == 0) {
UILabel *lbl1 = [[UILabel alloc] initWithFrame:CGRectMake(20, 10, 100, 30)];
lbl1.text = #"Some Text";
[cell addSubview:lbl1];
switch = [[UISwitch alloc] initWithFrame:CGRectMake(190, 10, 200, 30)];
[switch setOn:NO];
switch.tag = 1;
[switch addTarget:self action:#selector(switchTapped:) forControlEvents:UIControlEventChanged];
[cell addSubview:switch];
}
}
// Below is my switchTapped method:
- (void) switchTapped: (id)sender {
UISwitch *tapSwitch = (UISwitch *)sender;
switch (tapSwitch.tag) {
case 1:
if (tapSwitch.on) {
// do something
}
else {
// do something
}
break;
case 2:
if (tapSwitch.on) {
// do something
}
else {
// do something
}
break;
}
Am I doing anything wrong over here?
Thank You.

Answer 1

You're using really nasty code which regenerates the cell each time it's needed:
if(cell != nil)
{
cell = nil;
}
if (cell == nil)
{
...
}
Do you bind the state of your switch to some retained object (e.g. Item model object, where single cell reflects an Item)?

Answer 2

This is how I write my cell drawing code:
Basically, within my if(cell == nil) { ... } I do all the "initWithFrame". Anything outside that, I simply set the value such as label text. Don't do the initWithFrame outside the if(cell == nil) {...} block of code.
-(UITableViewCell *) tableView:(UITableView *) tableView cellForRowAtIndexPath:(NSIndexPath *) indexPath
{
static NSString *reusableCell = #"reusableCell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reusableCell];
if(cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reusableCell] autorelease];
thumbnail = [[UIImageView alloc] initWithFrame:CGRectMake(5, 5, 106, 81)];
feedTitle = [[UILabel alloc] initWithFrame:CGRectMake(116, 3, [IOSDevice screenWidth] - 140, 25)];
postDate = [[UILabel alloc] initWithFrame:CGRectMake(116, 10, [IOSDevice screenWidth] - 140, 50)];
description = [[UILabel alloc] initWithFrame:CGRectMake(116, 45, [IOSDevice screenWidth] - 140, 50)];
// setting tag reminders so we can identify the element to replace
[thumbnail setTag:1];
[feedTitle setTag:2];
[postDate setTag:3];
[description setTag:4];
[[cell contentView] addSubview:thumbnail];
[[cell contentView] addSubview:feedTitle];
[[cell contentView] addSubview:description];
[[cell contentView] addSubview:postDate];
[thumbnail release];
[feedTitle release];
[description release];
[postDate release];
}
thumbnail = (UIImageView *)[[cell contentView] viewWithTag:1];
feedTitle = (UILabel *)[[cell contentView] viewWithTag:2];
postDate = (UILabel *)[[cell contentView] viewWithTag:3];
description = (UILabel *)[[cell contentView] viewWithTag:4];
[feedTitle setBackgroundColor:[UIColor clearColor]];
[feedTitle setFont:[UIFont fontWithName:#"Helvetica-Bold" size:16]];
[feedTitle setTextColor:[UIColor colorWithRed:0.215 green:0.215 blue:0.215 alpha:1.0]];
[description setBackgroundColor:[UIColor clearColor]];
[description setFont:[UIFont fontWithName:#"Helvetica" size:12]];
[description setTextColor:[UIColor colorWithRed:0.328 green:0.328 blue:0.328 alpha:1.0]];
[description setNumberOfLines:2];
[description setLineBreakMode:UILineBreakModeWordWrap];
[postDate setBackgroundColor:[UIColor clearColor]];
[postDate setFont:[UIFont fontWithName:#"Helvetica" size:12]];
[postDate setTextColor:[UIColor colorWithRed:0.707 green:0.180 blue:0.141 alpha:1.0]];
[thumbnail setImage:[[items objectAtIndex:[indexPath row]] objectForKey:#"thumb"]];
[feedTitle setText:[[items objectAtIndex:[indexPath row]] objectForKey:#"title"]];
[description setText:[[items objectAtIndex:[indexPath row]] objectForKey:#"summary"]];
// Format date
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateStyle:NSDateFormatterLongStyle];
[dateFormatter setTimeStyle:NSDateFormatterShortStyle];
[postDate setText:[dateFormatter stringFromDate:[[items objectAtIndex:[indexPath row]] objectForKey:#"date"]]];
[cell setSelectionStyle:UITableViewCellSelectionStyleNone];
[cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
if([feedList contentOffset].y < -50)
{
shouldUpdate = TRUE;
[activityIndicator stopAnimating];
[feedList setContentOffset:CGPointMake(0, -30) animated:NO];
[self loadData];
loadingLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, -25, [IOSDevice screenWidth], 20)];
[loadingLabel setText:#"Loading New Data"];
[loadingLabel setTextAlignment:UITextAlignmentCenter];
[loadingLabel setBackgroundColor:[UIColor clearColor]];
[loadingLabel setTextColor:[UIColor colorWithRed:0.215 green:0.215 blue:0.215 alpha:1.0]];
[loadingLabel setFont:[UIFont fontWithName:#"Helvetica-Bold" size:14]];
reloadingSpinner = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(70, -25, 20, 20)];
[reloadingSpinner setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleGray];
[reloadingSpinner startAnimating];
[reloadingSpinner setHidesWhenStopped:YES];
[feedList addSubview:reloadingSpinner];
[feedList addSubview:loadingLabel];
}
return cell;
}