validateMenuItem: not called

Question

I'm facing a weird situation. I've got an NSMenu with a submenu in it. The submenu's contents are populated programmatically. In my validateMenuItem: method, I can see all items being checked (the parent's items) as well as the subitems (once I click on a submenu), except for those in my auto-populated submenu.

Why is that? Am I doing something wrong? Any ideas on how to fix that?

And these menu items operate normally otherwise (i.e. when you select them they fire their action method)? — trojanfoe, Mar 03 '13 at 10:27
@trojanfoe Just found the answer (pretty simple to be honest...) - I'll post it right now. — Dr.Kameleon, Mar 03 '13 at 10:30
@trojanfoe All of the menu items' actions were implemented in the controller, while that one specific submenu's subitems' actions were not. Thus, the `validateMenuItem:` method was not to be called. (Frustrating... given that I was struggling with it 2 hours before posting it in SO (and then answering it myself after 10 minutes... lol)) — Dr.Kameleon, Mar 03 '13 at 10:35
Just talking about a problem is often enough to allow you to solve it yourself. — trojanfoe, Mar 03 '13 at 10:36

score 17 · Accepted Answer · answered Mar 03 '13 at 10:32

17

Here is the solution :

Cocoa looks for the validateMenuItem: method in the Class where the NSMenuItem's action selector is.

So, if your NSMenuItem's action selector (e.g. @selector(someSelector:)) is implemented in SomeClass, then make sure you have a validateMenuItem: method in SomeClass too, if you want to validate the corresponding menu items.

answered Mar 03 '13 at 10:32

Dr.Kameleon

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Don't you target the *First Responder* with your action? – trojanfoe Mar 03 '13 at 10:35
@trojanfoe Nope, I am not. All actions are linked to specific classes. Should I target the First Responder? – Dr.Kameleon Mar 03 '13 at 10:36
1

I guess it depends on the App, but in my Document Based App, I have all menus targeting *First Responder* I think. – trojanfoe Mar 03 '13 at 10:37
Well, First Responder is one of the things I've been tempted to use for quite a long time, but given (probably the control-freak part of my ... coding nature... lol) that I want to know 100% what-goes-where and what-does-what I haven't tried it so far (and perhaps it's not the best decision ever). Btw, the (quite huge) project I'm currently working on **is** indeed a Document-Based app too (but not in the strict Cocoa (see : `NSDocument`) sense...), so your input could be of some help. Thanks, mate! :-) – Dr.Kameleon Mar 03 '13 at 10:39
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Id urge you to try first responder :) It helps quite often – Daij-Djan Mar 03 '13 at 10:43
Well I believe the real value of using the *First Responder* is the context-sensitive nature of the menu items. You only get one set of menu items, so you want things like `Edit > Copy` to relate to whatever is selected in the current document. This concept can be applied to most menu items I think. – trojanfoe Mar 03 '13 at 10:44
@trojanfoe Well, the *Edit* menu is the one I'm most worried about. Since, guess what, my app **is** an editor (see: the one you'll most likely be using in a while ... lol) but not a very Cocoa Controls -compliant one either... So, actions - though seemingly the usual ones - don't correspond to their traditionally defined counterparts... – Dr.Kameleon Mar 03 '13 at 11:01

score 5 · Answer 2 · answered Jul 28 '19 at 08:03

@Dr.Kameleon has the right answer.

I'll add one small point to update it if that's OK? My code broke recently in this area and stopped calling validateMenuItem: when it was working before. I didn't notice because the only symptom was a menu item no longer disabled when it should.

The issue was Swift 4. The method must be attributed with @objc. In earlier versions of Swift, inheriting from NSObject, NSViewController, etc. was enough but that changed with the newer versions of Swift, 4 and 5.

p.s. It seems it is fine to put the method in an extension.

Darkwonder · Answer 3 · 2020-06-29T10:14:06.100

The above answers did not help me to solve my problem. I have created a separate project to understand when the validateMenuItem(:) method is called.

The validateMenuItem(:) method will be called only if:

Conform to NSMenuItemValidation in the class which implements the NSPopUpButton.
All NSMenuItems must have an action and target set to the object which implements the NSMenuItemValidation protocol.
Implement the validateMenuItem(:) method.
Implement the dummyAction(:) method for NSMenuItem which doesn't do anything.

The NSPopUpButton "Items: Autoenables" autoenablesItems must be set

Version 11.5 (11E608c) , Swift 5.0, DP: macOS 10.15.

Code:

import Cocoa
// 1) Conform to NSMenuItemValidation in the class which implements the NSPopUpButton.

class NSMenuItemValidationTestViewController: NSViewController, NSMenuItemValidation {
@IBOutlet weak var popupButton: NSPopUpButton!

// MARK: - ViewController lifecycle

override func viewDidLoad() {
    super.viewDidLoad()
    // .target and .action are set programmatically because menus are mostly build programmatically.
    // 2) All NSMenuItems must have an action and target set to the object which implements the
    // NSMenuItemValidation protocol.
    self.popupButton?.menu?.items.forEach{( $0.target = self )}
    self.popupButton?.menu?.items.forEach{( $0.action = #selector(dummyAction(_:)) )}
}

// MARK: - NSMenuItemValidation
// 3) Implement the validateMenuItem(:) method.
func validateMenuItem(_ menuItem: NSMenuItem) -> Bool {
    print("Function: \(#function), line: \(#line)")
    return true
}

// 4) Implement the dummyAction(:) method for NSMenuItem which doesn't do anything
@IBAction func dummyAction(_ sender: NSMenuItem?) {
    print("Function: \(#function), line: \(#line)")    }


}

// 5) The NSPopUpButton "Items: Autoenables" checkbox must be set to true in storyboard.
// or
// self.popupButton?.menu?.autoenablesItems = true

TODO: Github link to source code. (Coming soon).

validateMenuItem: not called

3 Answers3