Add new UITableView row with custom text

Question

Using this code

- (IBAction)testAdd:(id)sender 
{
    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:self.numberOfRows inSection:0];

    [self.tableView beginUpdates];
    self.numberOfRows++;
    [self.tableView insertRowsAtIndexPaths:@[indexPath]withRowAnimation:UITableViewRowAnimationBottom];
    [self.tableView endUpdates];


}

I'm able to add a new item to a tableView via an 'add' button on the app. This basically adds an item identical to the item already on the table that preceded it. For example, I have a tableview with the first row displaying a string "TEST", hitting add adds another row that displays "TEST". I would like to be able to pass in a custom value for the new row, so hitting add outputs a row with say "NEWTHING".

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"UITableViewCell" forIndexPath:indexPath];

    // Configure the cell...

    cell.textLabel.text = self.val2;

    return cell;
}

My data source is actually another view controller that takes user inputs and sends it to my tabelViewController, with the text for the item as "val2". What I actually want to achieve is the ability to hit add, go back to the user input view controller, get the new data and send it back to my tableViewController to be displayed

Answer 1

What you're asking, is the kinda stuff that is to be done in -cellForRowAtIndexPath: (most of the times, it depends on the way you have designed your datasource) but if it doesn't matter to you, then you can do:

- (IBAction)testAdd:(id)sender 
{
    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:self.numberOfRows
                                                inSection:0];
    self.numberOfRows++;

    [self.tableView beginUpdates];
    [self.tableView insertRowsAtIndexPaths:@[indexPath]
                          withRowAnimation:UITableViewRowAnimationBottom];
    [self.tableView endUpdates];

    UITableViewCell *cell = [self.tableView cellForRowAtIndexPath:indexPath];
    [cell.textLabel setText:@"NEWTHING"];
}

But note that when you scroll far up/down and return to this cell, it will most probably show "TEST" (that's where -cellForRowAtIndexPath: will show it's true purpose)

PS: Include your -cellForRowAtIndexPath: method implementation in the question if you want to proceed further

---

EDIT:

Your -cellForRowAtIndexPath is too static... in the sense that it simply sets self.val2 to cell.textLabel.
Lets say you start with 10 rows, -cellForRowAtIndexPath will be called 10 times and every time, it will set self.val2 onto the current cell's textLabel.
Now... when you add one row (on a button tap), the -cellForRowAtIndexPath will be called for the 11th cell and the same^* text will be set to it.
^{*this technically happened but we quickly changed the cell's text}

Basically, the tableView doesn't know how to differentiate between an existing cell and a new added cell because the datasource itself is not dynamic.

To direct the tableView on how to handle different cells, we need to create a more dynamic datasource.

There are different approaches use but I'd generally do it this way:

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.val2 = @"TEST";

    //declare "NSMutableArray *arrDatasource;" globally
    //this will be the soul of the tableView
    arrDatasource = [[NSMutableArray alloc] init];

    int i_numberOfCells = 10;

    //populate beginning cells with default text
    for (int i = 0; i < i_numberOfCells; i++) {
        NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
        [dictionary setObject:self.val2 forKey:@"displayText"];

        [arrDatasource addObject:dictionary];
    }
}

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

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    //return number of objects in arrDatasource
    return arrDatasource.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"UITableViewCell" forIndexPath:indexPath];

    //pick up value for key "displayText" and set it onto the cell's label
    [cell.textLabel setText:arrDatasource[indexPath.row][@"displayText"]];
    //this will be dynamic in nature because you can modify the contents
    //of arrDatasource and simply tell tableView to update appropriately

    return cell;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    //make indexPath of new cell to be created
    NSIndexPath *indexPathNEXT = [NSIndexPath indexPathForItem:arrDatasource.count inSection:0];

    //add the appropriate contents to a dictionary
    NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
    [dictionary setObject:@"NEWTHING" forKey:@"displayText"];

    //add the dictionary object to the main array which is the datasource
    [arrDatasource addObject:dictionary];

    //add it to tableView
    [self.tableView beginUpdates];
    [self.tableView insertRowsAtIndexPaths:@[indexPathNEXT]
                          withRowAnimation:UITableViewRowAnimationAutomatic];
    [self.tableView endUpdates];
    //this ends up calling -cellForRowAtIndexPath for the newly created cell
    //-cellForRowAtIndexPath shows the text (you put in the dictionary in this method above)
}

PS: -cellForRowAtIndexPath: is called whenever cell updates or refreshes or needs to be displayed and so this method needs to be implemented properly