Quickies for NSTableView

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General

• Disabling "Return moves editing to next cell" in TableView [permalink]
  When you edit cells in a tableview, pressing return, tab, or shift-tab will end the current editing (which is good), and starts editing the next cell. But of times you don't want that to happen - the user wants to edit an attribute of a given row, but it doesn't ever want to do batch changes to everything.

  To make editing end, you need to subclass NSTableView and add code to catch the textDidEndEditing delegate notification, massage the text movement value to be something other than the return and tab text movement, and then let NSTableView handle things.

  // make return and tab only end editing, and not cause other cells to edit
  
  - (void) textDidEndEditing: (NSNotification *) notification
  {
      NSDictionary *userInfo = [notification userInfo];
  
      int textMovement = [[userInfo valueForKey:@"NSTextMovement"] intValue];
  
      if (textMovement == NSReturnTextMovement
          || textMovement == NSTabTextMovement
          || textMovement == NSBacktabTextMovement) {
  
          NSMutableDictionary *newInfo;
          newInfo = [NSMutableDictionary dictionaryWithDictionary: userInfo];
  
          [newInfo setObject: [NSNumber numberWithInt: NSIllegalTextMovement]
                   forKey: @"NSTextMovement"];
  
          notification =
              [NSNotification notificationWithName: [notification name]
                                         object: [notification object]
                                         userInfo: newInfo];
  
      }
  
      [super textDidEndEditing: notification];
      [[self window] makeFirstResponder:self];
  
  } // textDidEndEditing

  (Thanks to Steven Jacowski for a tweak that ends editing on clicks on different cells)

• Dragging feedback only between rows [permalink]
  When rearranging rows in a tableview, the user feedback should just go between rows (the whole-row highlighting is confusing). In the drop validation method only let things through for NSTableViewDropAbove

  - (NSDragOperation) tableView: (NSTableView*) tableView
                   validateDrop: (id ) info
                    proposedRow: (int) row
          proposedDropOperation: (NSTableViewDropOperation) op
  {
      int result = NSDragOperationNone;
  
      if (op == NSTableViewDropAbove) {
          result = NSDragOperationMove;
      }
  
      return (result);
  
  } // validateDrop
  
  

• Handling double-clicks [permalink]
  Use NSTableView's -setDoubleAction: method, and supply it a standard IBAction-style method selector.

  You may need to also do -setTarget:. double-clicks get sent if the column isn't editable, so you may need to grab the column and do a -setEditable: NO on it.

• Making a table view a drag source [permalink]
  If you want to make your NSTableView a source for a drag and drop operation, you need to implement

  - (BOOL) tableView: (NSTableView *) tableView
           writeRowsWithIndexes: (NSIndexSet *) rowIndexes
           toPasteboard: (NSPasteboard *) pboard;
  

  in your table view data source (and don't forget to hook up the datasource if you use bindings to populate the tableview)

  (Thanks to Rob Rix for updating this with more modern API)

• Preventing the return key from editing the next cell [permalink]
  The default tableview behavior, when editing a row, is to move the field editor to the next cell when the user commits editing using the Return key. If you want Return to commit the editing and dismiss the field editor, subclass NSTableView and add this:

  - (void) textDidEndEditing: (NSNotification *) notification
  {
      NSDictionary *userInfo;
      userInfo = [notification userInfo];
  
      NSNumber *textMovement;
      textMovement = [userInfo objectForKey: @"NSTextMovement"];
  
      int movementCode;
      movementCode = [textMovement intValue];
  
      // see if this a 'pressed-return' instance
  
      if (movementCode == NSReturnTextMovement) {
          // hijack the notification and pass a different textMovement
          // value
  
          textMovement = [NSNumber numberWithInt: NSIllegalTextMovement];
  
          NSDictionary *newUserInfo;
          newUserInfo = [NSDictionary dictionaryWithObject: textMovement
                                      forKey: @"NSTextMovement"];
  
          notification = [NSNotification notificationWithName:
                                             [notification name]
                                         object: [notification object]
                                         userInfo: newUserInfo];
      }
  
      [super textDidEndEditing: notification];
  
  } // textDidEndEditing
  

• Putting the ordering triangles in table columns [permalink]
  Put this somewhere (maybe in your mouseDownInHeaderOfTableColumn or didClickTableColumn:

      NSImage *indicatorImage;
      if (sortAscending) {
          sort your data ascending
          indicatorImage = [NSImage imageNamed: @"NSAscendingSortIndicator"];
      } else {
          sort your data descending
          indicatorImage = [NSImage imageNamed: @"NSDescendingSortIndicator"];
      }
      sortAscending = !sortAscending;
  
      [tableView setIndicatorImage: indicatorImage
                     inTableColumn: tableColumn];
  
      [tableView reloadData];
  
  

• Responding to selection changes [permalink]
  

  - (void) tableViewSelectionDidChange: (NSNotification *) notification
  {
      int row;
      row = [tableView selectedRow];
  
      if (row == -1) {
          do stuff for the no-rows-selected case
      } else {
          do stuff for the selected row
      }
  
  } // tableViewSelectionDidChange

  If you have more than one tableview, the notification's object is the tableview that had the selection change.

• Table View drag destination on or between rows [permalink]
  When your NSTableView is a drag destination, you may want to support both dragging onto existing objects (to replace them, or augment them with some new attribute the user is dragging over) and support dragging between existing objects (to insert a new one in between. To get this behavior, you need to use NSTableView's -setDropRow:dropOperation:, like so:

  - (NSDragOperation) tableView: (NSTableView *) view
                   validateDrop: (id ) info
                    proposedRow: (int) row
          proposedDropOperation: (NSTableViewDropOperation) op
  {
      // have the table highlight on-row / between-row correctly
      [view setDropRow: row
            dropOperation: op];
  
      // or use whatever drag operation is appropriate
      NSDragOperation dragOp = NSDragOperationCopy;
  
      return (dragOp);
  
  } // validateDrop

  and in the acceptDrop method, look at the operation:

  - (BOOL) tableView: (NSTableView *) view
          acceptDrop: (id ) info
                 row: (int) row
       dropOperation: (NSTableViewDropOperation) op
  {
      if (op == NSTableViewDropOn) {
          // replace existing
  
      } else if (op == NSTableViewDropAbove) {
          // add new
  
      } else {
          NSLog (@"unexpected operation (%d) in %s",
                 op, __FUNCTION__);
      }
  
      // documentation doesn't actually say what this signifies
      return (YES);
  
  } // acceptDrop

• Tableview DataSource methods [permalink]
  Your datasource needs to implement these two bad boys:

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


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