NSTableView 下有个属性 _editingCell，可通过以下方式获取：
NSCell *tmpCell = objc_getAssociatedObject(textView, @"EditingCell");
@interface NSTableView : NSControl <NSUserInterfaceValidations, NSTextViewDelegate, NSDraggingSource, NSAccessibilityTable>
{
/* All instance variables are private */
NSTableHeaderView *_headerView;
NSView *_cornerView;
NSMutableArray *_tableColumns;
NSCell *_editingCell;
// NOTE: accessing the _delegate or _dataSource ivars directly is not supported! They are opaque objects, and may not represent the real delegate.
id _delegate;
id _dataSource;
NSSize _intercellSpacing;
CGFloat _rowHeight;
NSInteger _lastSelectedColumn;
NSInteger _lastSelectedRow;
NSInteger _editingRow;
NSInteger _editingColumn;
NSMutableIndexSet *_selectedColumns;
NSMutableIndexSet *_selectedRows;
id _columnDragInfoX;
NSColor *_backgroundColor;
NSColor *_gridColor;
id _rowDataX;
id _reserved3;
SEL _reserved4;
SEL _doubleAction;
NSRect _rectOfLastColumn;
NSInteger _lastCachedRectColumn;
NSRect _rectOfLastRow NS_DEPRECATED_MAC(10_0, 10_7); // UNUSED and will be removed
NSInteger _lastCachedRectRow NS_DEPRECATED_MAC(10_0, 10_7); // UNUSED and will be removed
_TvFlags _tvFlags;
id _reserved;
}
