处理NSMenuDelegate menuWillOpen以更改目标 [英] Handling NSMenuDelegate menuWillOpen for changing targets

问题描述

有很多有关使用menuWillOpen的答案.他们都解释说，首先需要设置菜单的代表.

There are lots of related answers about using menuWillOpen. They all explain that one needs to set the menu's delegate first.

当我只有一个目标(例如首选项"窗口或主应用程序)时，这很容易.

This is easy when I have just one target, like a Preferences window or the main application.

但是如果我有一个基于文档的应用程序，并且我需要活动文档句柄menuWillOpen怎么办?然后委托不再是常量.

But what if I have a document based app, and I need to have the active document handle menuWillOpen? Then the delegate isn't a constant any more.

处理此问题的正确方法是什么?我是否必须将委托设置为单个对象(如AppDelegate)，然后将调用转发到活动视图控制器(但如何正确完成)?还是还有其他优雅的方式?

What's the proper way to handle this? Do I have to set the delegate to a single object (like the AppDelegate) and then forward the call to the active view controller (but how is that done correctly)? Or is there some other elegant way?

推荐答案

我想出了这个似乎可行的代码:

I came up with this code which appears to work:

// This is in my AppDelegate class, and the NSMenu's delegate points to it:
- (void)menuWillOpen:(NSMenu *)menu {
    // Forward to active document controller
    NSWindow *mainWindow = [NSApplication sharedApplication].mainWindow;
    NSResponder *r = mainWindow.firstResponder;
    while (r) {
        if ([r respondsToSelector:_cmd]) {
            [(id<NSMenuDelegate>)r menuWillOpen:menu];
            return;
        }
        r = r.nextResponder;
    }
}

假定响应者链下的控制器实现了menuWillOpen:

It assumes that a controller down the responder chain implements menuWillOpen:

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