Automatic table column Indentifier in NSTableView

问题

After bit of research, I was able to populate the NSTableView with some date via the "identifier way" like you assign unique identifier to each column. However, I would like to now if there is a way to populate NSTableView without providing the identifier to the columns and how?

To be more clear - the use of automatic table column identifier, which is slightly described here: About the automatic table column identifier and and I find a way how to enumerate or get the index of the column by this expression:

//in the objectValueForTableColumn blah blah blah method

int columnIndex = [[aTableColumn identifier] intValue];
return [[myArray objectAtIndex: rowIndex] objectAtIndex: columnIndex];

However, the thing is that the columnIndex is equal to 0 in each column. (I have for example 4 columns in NSTableView)

Can you please help me how to display the data without setting the identifier? Thank you very much!

回答1:

First of all you should not get the index of the column, as the columns can be dragged and hence its index can be changed. However you can do as:

- (id)tableView:(NSTableView *)tableView objectValueForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row{

    if ([tableView tableColumns][0] == tableColumn) {
        return [self.array[row] firstName];
    }
    else if ([tableView tableColumns][1] == tableColumn) {
        return [self.array[row] lastName];
    }
}

The other way around is to check with the table header cell title. Using this you can decide what value to fill in the column. Something like: (But here you need to set the column header manually)

- (id)tableView:(NSTableView *)tableView objectValueForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row{

    NSCell *headerCell = [tableColumn headerCell];

    if ([[headerCell title] isEqualToString:@"First Name"]) {
        return [self.array[row] firstName];
    }
    else if ([[headerCell title] isEqualToString:@"Last Name"]) {
        return [self.array[row] lastName];
    }

    return nil;
}

Also you can opt for Cocoa-Binding, here no need to use identifiers!!!

Edit:

As you don't have class, infact you are dealing with basic C-array. But the delegate returns id so you need to typecast it to some Obj-C object. In following case I use NSString. See the screen shot :

回答2:

But the column identifier is not an Integer... and therefore your "intValue" will always bring a 0 out of it.

The column Identifier (whether automatic, or provided by the user when defining the table, either programmatically or using the UI editor) is an NSString. It is used not only for finding an NSColumn, but also for automatically persisting column attributes in NSUserDefaults.

Another wrong assumption - is that the column identifier has to do with its index. It is NOT. Columns can be re-arranged (by dragging them around, or programmatically) so their index can change.

So - to adapt your code sample to working with column identifiers - I would recommend that you will not work with a 2-dimensional array (with indexes for both rows and columns) but rather use an NSDictionary for the per-column information, where the key (NSString) will be the column identifier, and the value - the value of the cell you need.

So: indexes for rows, keys for column identifiers, your sample lines would look like this:

//in the objectValueForTableColumn blah blah blah method

NSString columnIdentifier = [aTableColumn identifier];
return [[myArray objectAtIndex: rowIndex] valueForKey: columnIdentifier];

来源：https://stackoverflow.com/questions/22375689/automatic-table-column-indentifier-in-nstableview

标签

objective-c

cocoa

nstableview