Hey there! Let's troubleshoot why your viewForTableColumn:row: delegate method isn't firing even though numberOfRowsInTableView works. Based on what you've shared, here are the most likely culprits to check:

1. Container View Layout & Table Visibility Issues #

Since your table lives inside a container view, double-check that the table isn't being hidden or has zero dimensions:

• Verify the table's isHidden property is set to NO
• Print the table's frame in viewDidAppear: (e.g., NSLog(@"Table frame: %@", NSStringFromRect(self.tableView.frame))) — if the width/height is 0, the system won't attempt to load cell views
• Ensure the container view's auto layout constraints are properly pinning the table to its edges, so the table gets rendered with actual size

2. Table View Content Mode Mismatch #

NSTableView has two content modes, and this is a super common gotcha:

• Open Interface Builder, select your table, check the Attributes Inspector
• Make sure the "Content Mode" is set to View Based — if it's set to Cell Based, the table will call tableView:objectValueForTableColumn:row: instead of your viewForTableColumn:row: method

3. Cell Identifier Exact Match #

You mentioned setting the appCell identifier, but even tiny mismatches break this:

• In IB, select your NSTableCellView, check its Identity Inspector to confirm the identifier is exactly appCell (no extra spaces, correct capitalization)
• In your viewForTableColumn:row: method, ensure you're using the exact same string when calling makeViewWithIdentifier:owner: (e.g., @"appCell" not @"AppCell" or @"appcell")

4. Delegate/DataSource Binding Validation #

Even if you declared the protocols and set the delegates, there could be hidden issues:

• If using IB bindings: Open the Connections Inspector for your table, confirm the delegate and dataSource outlets are connected directly to your ViewController (no broken connections)
• If setting via code: Ensure you're setting self.tableView.delegate = self and self.tableView.dataSource = self after the table is initialized (e.g., in viewDidLoad or awakeFromNib, not in init where the table might not exist yet). Print the values afterward to confirm they aren't nil:

  NSLog(@"Table delegate: %@, dataSource: %@", self.tableView.delegate, self.tableView.dataSource);
  

5. Timing of reloadData #

Make sure you're triggering a reload after your data source is populated:

• If your data loads asynchronously, call [self.tableView reloadData] after the data is ready (not just in viewDidLoad when the array might still be empty)
• Even if numberOfRowsInTableView returns a non-zero number, the table won't request cell views until you explicitly call reloadData

Here's a quick sanity-check code snippet for reference:

// ViewController.m
- (void)viewDidLoad {
    [super viewDidLoad];
    
    // Confirm delegate/dataSource setup
    self.tableView.delegate = self;
    self.tableView.dataSource = self;
    
    // Load your data (sync or async)
    [self fetchData];
}

- (void)fetchData {
    // Example async data load
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        self.dataArray = [self loadDataFromSource];
        
        // Reload on main thread!
        dispatch_async(dispatch_get_main_queue(), ^{
            [self.tableView reloadData];
        });
    });
}

- (NSInteger)numberOfRowsInTableView:(NSTableView *)tableView {
    return self.dataArray.count;
}

- (NSView *)tableView:(NSTableView *)tableView viewForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row {
    NSTableCellView *cell = [tableView makeViewWithIdentifier:@"appCell" owner:self];
    if (cell) {
        cell.textField.stringValue = self.dataArray[row];
    }
    return cell;
}

内容的提问来源于stack exchange，提问作者John