View based NSTableView editing

I'm not sure what I'm doing wrong. Since I couldn't find any other questions (or even documentation) about this, it seems do be normally working without problems for other people.

I'm simply trying to get a view based NSTableView to do support editing of it's content. I.e. the app displays a NSTableView with one column and several rows, containing a NSTextField with some content. I want to be able to (double) click on a cell and edit the cell's content. So basically the normal behavior of a cell based NSTableView where the tableView:setObjectValue:forTableColumn:row: method is implemented.

I analyzed the Complex TableView example in the TableViewPlayground sample code from Apple (which is supporting editing of cell content), but I cannot find the setting/code/switch which is enabling the editing.

Here's a simple sample project (Xcode 6.1.1, SDK 10.10, storyboard based):

Header:

#import <Cocoa/Cocoa.h>

@interface ViewController : NSViewController

@property (weak) IBOutlet NSTableView *tableView;

@end

Implementation:

#import "ViewController.h"

@implementation ViewController
{
    NSMutableArray* _content;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    _content = [NSMutableArray array];

    for(NSInteger i = 0; i<10; i++) {
        [_content addObject:[NSString stringWithFormat:@"Item %ld", i]];
    }
}

#pragma mark - NSTableViewDataSource
- (NSInteger)numberOfRowsInTableView:(NSTableView *)aTableView
{
    return _content.count;
}

#pragma mark - NSTableViewDelegate
- (NSView *)tableView:(NSTableView *)tableView viewForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row
{
    NSTableCellView* cell = [tableView makeViewWithIdentifier:@"CellView" owner:self];
    cell.textField.stringValue = _content[row];
    return cell;
}

- (IBAction)endEditingText:(id)sender {
    NSInteger row = [_tableView rowForView:sender];
    if (row != -1) {
        _content[row] = [sender stringValue];
    }
}
@end

The storyboard file looks like this:

The datasource and delegate of the table view are set to the view controller. When running this app, the table view displays the 10 test rows, but it is not possible to edit one of the rows.

Why is that? What did I miss here?

I double checked all attributes of the NSTableView (and it's contents) to be the same as in the TableViewPlayground sample from Apple. And after several hours of searching the documentation and internet for helpful hints without any success, I'm kind of frustrated. All you can find on view based NSTableViews are non-editable samples or very vague information on editable content. And of course, there is tons of information, documentation and samples on editable, cell based NSTableViews...

A zip with my sample project is downloadable here: TableTest.zip

By default, each cell (instance of NSTableCellView) has an NSTextField sitting on it. When you're editing the cell, what you're in fact editing is this text field. Interface Builder makes this text-field non-editable:

All you need to do is set the Behaviour pop-up to Editable. Now you can edit the text-field with a return hit or a single-click.