撤销和重做在核心数据可可应用程序 - 这是正常的行为吗？ [英] Undo and Redo in core data cocoa application - is this normal behaviour?

问题描述

我有核心数据可可应用程序。我尝试不同的方式来使用绑定启用撤消和重做选项，我找不到一种方法如何做到。所以我做了2个IBActions，我现在有以下代码：（只有与问题相关的代码张贴，因为简单）

I have core data cocoa application. I was trying different ways to enable the undo and redo option using bindings, and I couldn't find a way how to do it. So I make 2 IBActions and I have now the following code: (only the code relevant to the question is posted due the simplicity)

- (void)windowDidLoad {
    self.appDelegate = (AppDelegate*)[[NSApplication sharedApplication] delegate];
    self.mObjContext = self.appDelegate.managedObjectContext;
}

- (IBAction)undoItemHasBeenClicked:(id)sender {
    [self.mObjContext undo];
}

- (IBAction)redoItemHasBeenClicked:(id)sender {
    [self.mObjContext redo];
}

这个代码一切正常，效果很好。但是，我不喜欢的是，即使我不做任何更改，撤消和重做项目菜单处于活动状态。如果我没有做任何更改，那么这两个选项应该不是灰色的，所以没有什么可撤销或重做？

Everything is fine with this code, it works just fine. However, what I don't like is that even if I don't make any changes, the undo and redo item menus are active. Shouldn't those 2 options be grayed if I have done no changes so there is nothing to undo or redo?

我在这里做错了，这是正常的行为吗？

Am I doing something wrong here or this is normal behavior? Any help will be deeply appreciated.

推荐答案

菜单项已启用，因为 undoItemHasBeenClicked 和 redoItemHasBeenClicked 可以执行。如果窗口的委托实现 windowWillReturnUndoManager：并返回上下文的undomanager，默认的撤消和重做菜单项应该工作。

The menu items are enabled because undoItemHasBeenClicked and redoItemHasBeenClicked can be executed. The default undo and redo menu items should work if the delegate of the window implements windowWillReturnUndoManager: and returns the undomanager of the context.

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