如何将 NSMenuItem（启用）的状态绑定到 NSNumber 的特定值？

Question

How do I bind a state of a NSMenuItem (enabled) to a specific value of an NSNumber ?

ie

if myNumber ==2 then my NSMenuItem should be enabled

I need to do this for several NSMenuItem:

ie

if myNumber = 3 then my second NSMenuItem should be enabled

thanks

Answer 1

If you want to use a transformer, I think you'd have to write it yourself, as in this example . It will register a class which defines a value transformer, which the system will then instantiate.

In case you want to register an instance as a value transformer, this doc has the details. The advantage if this will be that you can configure each instance differently without having to define a class for each situation.

Answer 2

I found ValueTransformer s to be too cumbersome for this. It gets much simpler than that. Just create a controller object like below

class FooMenuController: NSObject {

    @IBAction func selectedNumberChanged(sender: NSMenuItem) {
        UserDefaults.fooNumber = sender.tag
    }
}

extension FooMenuController: NSMenuItemValidation {

    func validateMenuItem(_ menuItem: NSMenuItem) -> Bool {
        let on = (menuItem.tag == UserDefaults.fooNumber)
        menuItem.state = on ? .on : .off
        return true
    }
}

In your MainMenu.xib drag out an NSObject instance from the library and set it to your FooMenuController subclass. Now set the action on every NSMenuItem to FooMenuController.selectedNumberChanged and its tag value to the number it should represent.

Voila.

Answer 3

Use IBOutlet to your NSButton and disable all the button from interface builder. then use If else condition and enable your button.

IBOutlet NSButton *my1;// Disable  
IBOutlet NSButton *my2; //Disable   
If(myNumber ==1)
 [my1 setState:NSOnState];
else If(myNumber ==2)
 [my1 setState:NSOnState];

Answer 4

您可以在 IB 中绑定它的（NSButton）“值”