Question

So I’ve been given an assignment in my Mobile apps class: make a color game app for the iphone.(The description of how to game works is at the top of the pasted viewcontroller.h file below.)

I’m very new to Objective-C and cocoa, but have managed to troubleshoot and fix a lot of things in this app. The problem I have right now is that I don’t know how to properly initialize and send UITableViewCells to the view. I’m confused because all of the tutorials I’ve found online use datasource methods to change different attributes of the UITableView and the cells as well. I’m not sure how these methods will interact with the controls I’ve already placed. I’m confused because I added them by the storyboard file, not by defining tableview attributes with datasource code.

My immediate issue is that my program won’t display the proper text to the cells textlabel and detailtextlabel.

I’ve looked everywhere online for UITableView and UITableViewCell tutorials, but they are all from years ago and I’m not sure if the advent of the storyboard has changed the way I would treat these controls.

All of the code I’ve written is either in the viewcontroller.m or viewcontroller.h files.

The method within ViewController.m file, that should call the cell and display text and detail text:

-(IBAction)enterClicked
{
//On enter- send instance colors to the colorTable row[i], perform comparisons and append     the resulting symbols to the instanceResults String. Send instanceResults string to the resultTable     row[i]. When game counter reaches 6, gameOver. If on comparisons check, the instanceColors are     the same as the gameColors, then the player wins.

    [self checkForLoss];

    if(!self.gameOver)
    {
    resultOfGuess = [self comparePlayerInputToGameColors:guessColors];

    [listOfGuesses addObject:guessColors];
    [listOfOutcomes addObject:resultOfGuess];

    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:_numberOfTurnsPlayed inSection:0];    

        UITableViewCell *thisCell = [[UITableViewCell alloc]      initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier];

        thisCell.textLabel.text = [self.listOfGuesses lastObject];
        thisCell.detailTextLabel.text = [self.listOfOutcomes lastObject];

    [guessColors setString:@""];

    if([self checkForWin:resultOfGuess])
        [UpdateLabel setText:@"You have won!"];
    else
        [UpdateLabel setText:@""];

    self.colorCounter = 0;
    self.isStepOne = YES;
    _numberOfTurnsPlayed++;
    }

    else
    {
        if([self checkForLoss])
        [UpdateLabel setText:@"You have lost!"];
    }
}

The UITableView DataSource Methods I’ve called at the bottom of the viewcontroller.m file:

    #pragma mark - UITableViewDataSource protocol


- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    if(section == 0)
        return @"Guesses:  Results:";
    return 0;
}

-(NSInteger) numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

-(NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 6;
}

-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath     *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if(cell == nil)
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleValue1     reuseIdentifier:CellIdentifier];
    }
    return cell;
}  

So my questions are: Can I change a control’s properties with datasource methods, if I created the controls through the storyboard? How do I properly display the text in a uitableview’s cells?

Edit/update: Thank you, I’ve used your advice jrturton, but now I’ve found something peculiar that may be the source of my problems. in my viewController.h file I’ve changed my header from

ViewController: UIViewController to ViewController: UITableViewController

Thinking that the datasource methods I call within the viewcontroller files have to be able to call the same methods and properties of the class that I call in the header– Also, I see this done in other UITableView tutorial files.

The problem is that when I change the header to read– ViewController: UITableViewController — and I try to compile, I get this error:

Terminating app due to uncaught exception ‘NSInternalInconsistencyException’, reason: ‘-[UITableViewController loadView] loaded the “2-view-3” nib but didn’t get a UITableView.’
It compiles fine if I use just :UIViewController in the header file though.

Any ideas?

Further update: I”ve noticed within my storyboard that the only available ViewController object is a UIViewController object, while in the other tutorial files I’ve seen, this ViewController object is a UITableViewController object. I imagine this is my problem, but I can’t seem to switch my UIViewController object to a UITableViewController. All I can do is create a new one, which isn’t what I want, I imagine.

Answer 1

Your action method should update the data model (which I think it does, since it changes your listOfGuesses array). You then need to let your table view know that you have added or updated rows so that it can re-load them for you – check the UITableView documentation for reloading data or specific rows.

Creating a cell outside of the datasource methods isn’t going to let that cell appear in your table.

At the moment I’m guessing you have 6 empty cells in your table view? You need to populate the text and detail labels in your cellForRowAtIndexPath method. The difference now there are storyboards is that you don’t need to do the if (cell == nil) bit, as long as you have set the re-use identifier in your storyboard prototype cell then it will do all that for you. So your cellForRowAtIndexPath method can be reduced to:

-(UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath*)indexPath 
{     
    // This will dequeue or create a new cell based on the prototype in your storyboard    
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];

    // Put your actual configuration here based on your model array
    cell.textLabel.text = @"Hello";     

    return cell; 
} 

Further hints (this is homework so I’m not giving full samples)

• ‘indexPath.row` in the above method will give you the index from your model array that the cell refers to
• You have defined the table as having 6 rows, but you are adding items to your model arrays as you go – so when the table asks for row 5, and your model only has 3 entries, you need to deal with this. Consider changing the number of rows in the table dynamically and using table view methods to indicate that new rows have been added. Again, see the UITableView documentation for this.