Changing the default TableViewCell to custom subclass on button click - uitableview

Question

In a specific row I apply the default UITableViewCell class with a text label and an accessory button. When the accessory button is clicked, the cell is expanded and I want to change the UITableViewCell to a custom subclass I have created. However even if the cell is expanded, it won't switch to the custom subclass. Any ideas what to fix?
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
CGFloat result;
switch ([indexPath row])
{
case 2:
{
if ([indexPath isEqual:expandedRow]) {
return 100;
} else {
return 42;
}
}
return result;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
NSString *CellIdentifier;
NSString *CellIdentifierexp;
UITableViewCell *cell;
if (cell == nil) {
if (indexPath.row == 2) {
if ([indexPath isEqual:expandedRow]) {
cell = [[ExpandedCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifierexp];
}else{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
switch ([indexPath row])
{
case 2:
{
if ([indexPath isEqual:expandedRow]) {
NSLog(#"bike");
ExpandedCell *expandedcell = (ExpandedCell *)cell;
[expandedcell.text setText:self.descr];
NSArray *indexPathArray=[NSArray arrayWithObject:indexPath];
[self.tableview reloadRowsAtIndexPaths:indexPathArray withRowAnimation:UITableViewRowAnimationNone];
} else {
cell.textLabel.text = #"Description";
cell.accessoryType = UITableViewCellAccessoryDetailDisclosureButton;
cell.selectionStyle = UITableViewCellSelectionStyleNone;
cell.textLabel.textColor = UIColorFromRGB(0x2d5b3b);
// accessory type image
UIImage *image = [UIImage imageNamed:#"greenarrow.jpg"]; //or wherever you take your image from
UIButton *button = [[UIButton alloc]initWithFrame:CGRectMake(0,0, image.size.width, image.size.height)];
[button setBackgroundImage:image forState:UIControlStateNormal];
[button addTarget:self action:#selector(accessoryButtonTapped:withEvent:) forControlEvents:UIControlEventTouchDown];
button.userInteractionEnabled = YES;
cell.accessoryView = button;
}
break;
}
return cell;
}
- (void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath {
switch ([indexPath row])
{
case 2:
{
NSLog(#"Detail Disclosure Tapped");
expandedRow = indexPath;
[tableview beginUpdates];
[tableview endUpdates];
}
}
}
- (void) accessoryButtonTapped: (UIControl *) button withEvent: (UIEvent *) event
{
NSIndexPath * indexPath = [self.tableview indexPathForRowAtPoint: [[[event touchesForView: button] anyObject] locationInView: tableview]];
if ( indexPath == nil )
return;
[self.tableview.delegate tableView: self.tableview accessoryButtonTappedForRowWithIndexPath: indexPath];
}

Answer 1

Wow, you're doing something terribly wrong in here:
ExpandedCell *expandedcell = (ExpandedCell *)cell;
[expandedcell.text setText:self.descr];
NSArray *indexPathArray=[NSArray arrayWithObject:indexPath];
[self.tableview reloadRowsAtIndexPaths:indexPathArray withRowAnimation:UITableViewRowAnimationNone];
What you should do is slightly different. On a button tap you just call the [self.tableview reloadRowsAtIndexPaths:indexPathArray withRowAnimation:UITableViewRowAnimationNone]; then in the cellForRowAtIndexPath you should return the custom cell of your subclass in the method if the indexPath matches. No need to update the tableView there.
And need I say that this looks like a very very strange switch statement to me:
switch ([indexPath row])
{
case 2:
{
NSLog(#"Detail Disclosure Tapped");
expandedRow = indexPath;
[tableview beginUpdates];
[tableview endUpdates];
}
}
I would simply put it like this:
if (indexPath.row == 2){
NSLog(#"Detail Disclosure Tapped");
expandedRow = indexPath;
[tableview beginUpdates];
[self.tableview reloadRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationNone];
[tableview endUpdates];
}

Answer 2

Running the code
expandedRow = indexPath;
[tableview beginUpdates];
[tableview endUpdates];
when the accessory button is tapped will only ask the table view to update the row heights, it won't actually request a new cell for any row, so no cell type change will happen (until you scroll the row off screen and then back on again).
So, you need to actually reload the selected row, not just begin and end updates.

Answer 3

this here...
UITableViewCell *cell;
if (cell == nil) {
Local vars dont init to nil , they start as garbage, maybe nil , maybe not.
Either way you probably are not making it into the branch.
You are going to want to dequeue a cell from the table depending on whether its an expanded row or not
UITableViewCell *cell = nil;
if(thisIsAnExpandedRow) {
cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifierexp];
if(!cell) {
cell = [[ExpandedCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifierexp];
}
}
else {
cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
}