How to enable main menu item "copy"? - objective-c

Question

My main menu item "copy" is not clickable:
But I enable it in Xcode:
I haven't any Outlets of Main menu items in code.
What I can do?

Answer 1

“Enabling Menu Items” in Application Menu and Pop-up List Programming Topics says this:
By default, every time a user event occurs, NSMenu automatically enables and disables each visible menu item. You can also force a menu to update using NSMenu’s update method.
and this:
If the menu item’s target is not set (that is, if it is nil—typically if the menu item is connected to First Responder) and the NSMenu object is not a contextual menu, then NSMenu uses the responder chain (described in “The Responder Chain” in Cocoa Event Handling Guide) to determine the target. If there is no object in the responder chain that implements the item’s action, the item is disabled.
If there is an object in the responder chain that implements the item’s action, NSMenu then checks to see if that object implements the validateMenuItem: or validateUserInterfaceItem: method. If it does not, then the menu item is enabled. If it does, then the enabled status of the menu item is determined by the return value of the method.
By default (when you create a project using the “Cocoa Application” template), the Copy menu item's target is First Responder (nil) and the action is copy:. So you need to implement the copy: method on some item in your responder chain. That is sufficient to enable the menu item. If you want more precise control of when the menu item is enabled, you can also implement validateMenuItem: to check which menu item is being validated and return YES or NO as appropriate.
For example, the application delegate is in the responder chain. So you can add this method to CMAppDelegate:
- (IBAction)copy:(id)sender {
NSLog(#"%# %s", self, __func__);
}
That should be sufficient to enable the Copy menu item. Of course, choosing Edit > Copy will just log a message to the console. It's up to you to actually write the code that copies whatever the user has selected.
If you want more granular control, try giving the app delegate an outlet connected to the Copy menu item:
#interface AppDelegate : NSObject <NSApplicationDelegate>
#property (assign) IBOutlet NSWindow *window;
#property (strong) IBOutlet NSMenuItem *copyMenuItem;
#end
Hook up the outlet in MainMenu.xib. Then you can implement validateMenuItem: like this:
- (BOOL)validateMenuItem:(NSMenuItem *)menuItem {
if (menuItem == self.copyMenuItem) {
NSLog(#"%# %s %#", self, __func__, menuItem);
return [self shouldEnableCopyMenuItem];
}
return NO;
}