Xcode 26.1 can't subclass NSMenuItem

Using Swift
1

In Xcode 26.1, for a project with “Swift Language Version” set to swift6 I am getting for the following code I get errors:

Error1: Main actor-isolated initializer 'init(title:action:keyEquivalent:)' has different actor isolation from nonisolated overridden declaration

Error2: Main actor-isolated initializer 'init(coder:)' has different actor isolation from nonisolated overridden declaration

@MainActor class MenuItem: NSMenuItem { // error1

var userInfo: [String : Any] = [:]

init(label: String, action: Selector?, target: AnyObject?, userInfo: [String : Any]) {
    self.userInfo = userInfo
    super.init(title: label, action: action, keyEquivalent: "")
}

required init(coder decoder: NSCoder) { // error2
    super.init(coder: decoder)
}

}

I have now just discovered that if I set “Default Actor Isolation” to none isolated, then the error goes away, which seems very odd. Any help or suggestions.

2

just remove @MainActor

3

I had tried removing @MainActor that still gives the same error. If I mark the class with nonisolated, the error goes away.

However I would like to know why this is happening. Is it a bug or some kind of language feature. Interestingly if I subclass NSView it behaves as expected.

4

Sounds like you have MainActor default isolation turned on.

5

Sounds like you have MainActor default isolation turned on.

And if you want to keep it that way – mark the class nonisolated to opt-out.

6

Yes, the MainActor default isolation is on, and as I mentioned above, if I mark the class with noneisolated the error goes away.

What I don’t understand why this happens for NSMenuItem, and not for other Appkit classes that I tried such, as NSView.

7

Apple has marked NSView with NS_SWIFT_UI_ACTOR and didn't do that (yet?) with NSMenuItem.

In this particular case you may find these two properties useful for your purposes:

open var tag: Int
open var representedObject: Any?

instead of subclassing.

8

Thanks for the explanation. I will look into it.