NSOutlineViewDelegate Protocol Reference

Discussion

You can return a different data cell for any particular combination of table column and item, or a cell that will be used for the entire row (a full width cell). If tableColumn is non-nil, you should return a cell. Typically you should default to returning the result from [tableColumn dataCellForRow:row].

When each row (identified by the item) is being drawn, this method is first called with a nil value for tableColumn. At this time, you can return a cell that will be used to draw the entire row, acting like a group. If you do return a cell for the 'nil' table column, your implementations of the other corresponding datasource and delegate methods must be prepared to be invoked with a nil value for tableColumn. If do not return a cell for the 'nil' table column, the method will be called once for each column in the outline view, as usual.

Discussion

Values returned by this method should not include intercell spacing and must be greater than 0. Implement this method to support an outline view with varying row heights.

Discussion

If the cell in that row is an instance of NSTextFieldCell and contains only a string value, the “group row” style attributes are automatically applied for that cell.

Discussion

Implement this method if you want to control how type selection works. You should include startItem as a possible match, but do not include endItem.

It is not necessary to implement this method in order to support type select.

Discussion

This method may be called multiple times with one new index added to the existing selection to find out if a particular index can be selected when the user is extending the selection with the keyboard or mouse.

Implementation of this method is optional. If implemented, this method will be called instead of outlineView:willDisplayOutlineCell:forTableColumn:item:.

Discussion

The delegate can implement this method to disallow collapsing of specific items. For example, if the first row of your outline view should not be collapsed, your delegate method could contain this line of code:

return [outlineView rowForItem:item]!=0;

Discussion

The delegate can implement this method to disallow editing of specific cells.

Discussion

The delegate can implement this method to disallow expanding of specific items.

Discussion

When a column is initially dragged by the user, the delegate is first called with a newColumnIndex value of -1. Returning NO will disallow that column from being reordered at all. Returning YES allows it to be reordered, and the delegate will be called again when the column reaches a new location.

The actual NSTableColumn instance can be retrieved from the tableColumns array.

If this method is not implemented, all columns are considered reorderable.

Discussion

The delegate can implement this method to disallow selection of particular items.

For better performance and finer grain control over the selection, use outlineView:dataCellForTableColumn:item:.

Discussion

The delegate can implement this method to disallow selection of specific columns.

Discussion

Cell expansion can occur when the mouse hovers over the specified cell and the cell contents are unable to be fully displayed within the cell. If this method returns YES, the full cell contents will be shown in a special floating tool tip view, otherwise the content is truncated.

Discussion

Returning NO causes frameOfOutlineCellAtRow: to return NSZeroRect, hiding the cell. In addition, the row will not be collapsable by keyboard shortcuts.

This method will only be called for expandable rows.

Discussion

Normally, only selectable or selected cells can be tracked. If you implement this method, cells which are not selectable or selected can be tracked (and vice-versa). For example, this allows you to have a button cell in a table which does not change the selection, but can still be clicked on and tracked.

Discussion

Generally, this method will be called from keyDown: and the event will be a key event.

Discussion

By default, NSOutlineView iterates every row in the table, accesses a cell via preparedCellAtColumn:row:, and requests the cellSize to find the appropriate largest width to use.

For accurate results and performance, it is recommended that this method is implemented when using large tables. By default, large tables use a monte carlo simulation instead of interating every row.

Discussion

Implement this method if you want to control the string that is used for type selection. You may want to change what is searched for based on what is displayed, or simply return nil to specify that the given row and/or column should not be searched. By default, all cells with text in them are searched.

The default value when this delegate method is not implemented is:

[[outlineView preparedCellAtColumn:tableColumn row:[outlineView rowForItem:item]] stringValue]

and you can return this value from the delegate method if you wish.

Discussion

The delegate can modify cell to alter its display attributes; for example, making uneditable values display in italic or gray text.

Discussion

Informs the delegate that outlineView is about to display cell—an expandable cell (a cell that has the expansion symbol)—for the column and item specified by tableColumn and item. The delegate can modify cell to alter its display attributes.

This method is not invoked when outlineView is about to display a non-expandable cell.

Discussion

For example, if the user is editing a cell and enters an improper value, the delegate can prevent the user from selecting or editing any other cells until a proper value has been entered into the original cell. The delegate can implement this method for complex validation of edited rows based on the values of any of their cells.