Objective c NSOutlineView基于视图-仅在选中时显示按钮

我有一个NSOutlineView视图，基于一列标题+图像/文本/按钮

我只想在选中项目时显示按钮

我使用以下代码：

- (NSView *)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item {
   ....
  SidebarTableCellView *sidebarTableCellView = [outlineView makeViewWithIdentifier:@"MainCell" owner:self];
  [sidebarTableCellView.buttonProgramme setHidden:YES];
  if (outlineView.selectedRow == [outlineView rowForItem:item])
            [sidebarTableCellView.buttonProgramme setHidden:NO];

但它不工作，按钮总是隐藏的！我想不出是什么问题

---

编辑：if语句中的断点=>if语句从不匹配

我通过添加以下代码（viewForTableColumn中没有更改）解决了我的问题：

通过这样做，我们强制调用viewForTableColumn：当用户更改选择时

谢谢

- (void)outlineViewSelectionDidChange:(NSNotification *)notification {

    NSNotificationCenter * center = [NSNotificationCenter defaultCenter];
    [center removeObserver:self
                      name:@"NSOutlineViewSelectionDidChangeNotification"
                    object:self.sidebarOutlineView];

    NSInteger s = [self.sidebarOutlineView selectedRow];
    NSInteger lastSelectedRow = [[self.globalVariableDictionary objectForKey:@"lastSelectedRow"] integerValue];
    [self.globalVariableDictionary setObject:[NSNumber numberWithInteger:s] forKey:@"lastSelectedRow"];

    [self.sidebarOutlineView reloadDataForRowIndexes:[NSIndexSet indexSetWithIndex:s]
                                       columnIndexes:[NSIndexSet indexSetWithIndex:0]];
    [self.sidebarOutlineView reloadDataForRowIndexes:[NSIndexSet indexSetWithIndex:lastSelectedRow]
                                       columnIndexes:[NSIndexSet indexSetWithIndex:0]];
    [self.sidebarOutlineView selectRowIndexes:[NSIndexSet indexSetWithIndex:s] byExtendingSelection:NO];

    [center addObserver:self
               selector:@selector(outlineViewSelectionDidChange:)
                   name:@"NSOutlineViewSelectionDidChangeNotification"
                 object:self.sidebarOutlineView];

    [center addObserver:self
               selector:@selector(outlineViewSelectionDidChange:)
                   name:@"NSOutlineViewSelectionDidChangeNotification"
                 object:self.sidebarOutlineView];
}