Question

I have two UITableViewController classes, MainTableController and SubTableController.

From AppDelegate class I am calling MainTableController class.

At first this class is empty, and there is button named “show list” in this class.
When I click on this button I will go to SubTableController and there I have a list of actions in form of table.
Now if I choose to first cell action then that action name has to come on my first cell of table in MainTableController. But I am not able to print that name in table of MainTableController class.

In SubTableController:

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{   
    ActionList * actionListObj = [appDelegate.actionArray objectAtIndex:indexPath.row];  
    self.chooseActions = actionListObj.actionName;
    MainTableController * mainViewController = [[MainTableController alloc] init];      
    [mainViewController getAction:self.chooseActions];
    [self.navigationController dismissModalViewControllerAnimated:YES];
}

In MainTableController:

-(void) viewWillAppear:(BOOL)animated{
    [self reloadData];
}

-(void) reloadData{
    [self.myTableView reloadData];
}

-(void) getAction: (NSString *) actionChoose{        
    self.action = actionChoose;
    [self reloadData];
}       

-(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] autorelease];
    }
    // Configure the cell...
    cell.textLabel.text = self.action;
    return cell;
}

When I debug, in MainTableController I am getting the action in getAction method but in table cell text string is null.

Can anyone please help me regarding this?Where am I going wrong?

Answer 1

You are allocating and initializing a new view controller each time you select a cell in SubTableController.

MainTableController * mainViewController = [[MainTableController alloc] init];

and of course, it isn’t the one in place in the navigation stack.

You need to make these two controllers communicate.
I suggest that the sub view controller define a property on the main one, in order to message it when needed.

In SubTableController, add a property and synthesize it :

@property(readwrite, assign) MainViewController *mainViewController;
// and ...
@synthesize mainViewController;

Of course when you push the sub view controller, don’t forget to set the property.

// in main view controller
-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // alloc/init the sub VC
    subVCInstance.mainViewController = self;
    [self pushViewController:subVCInstance ......

Now when a row is selected in the sub one, message the main one, without alloc/init a new MainViewController object :

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{   
    ActionList * actionListObj = [appDelegate.actionArray objectAtIndex:indexPath.row];  
    self.chooseActions = actionListObj.actionName;
    //MainTableController * mainViewController = [[MainTableController alloc] init];      
    [self.mainViewController getAction:self.chooseActions];
    [self.navigationController dismissModalViewControllerAnimated:YES];
}

This should work just fine.