TIL about global actors in Swift

TIL about global actors in Swift: Swift proposal SE-0316 Global actors implemented in Swift 5.5.

Interesting that with await could be called func not marked with async:

class IconViewController: NSViewController {
  @MainActor @objc private dynamic var icons: [[String: Any]] = []
    
  @MainActor var url: URL? {
	didSet {
	  // Asynchronously perform an update
	  Task.detached { [url] in                   // not isolated to any actor
	    guard let url = url else { return }
	    let newIcons = self.gatherContents(url)
	    await self.updateIcons(newIcons)         // 'await' required so we can hop over to the main actor
	  }
	}
  }

  @MainActor private func updateIcons(_ iconArray: [[String: Any]]) {
    icons = iconArray
        
    // Notify interested view controllers that the content has been obtained.
    // ...
  }
}

Another interesting case calling with await a func not marked with async:

actor Counter {
  var value = 0
  
  @MainActor func updateUI(view: CounterView) async {
    view.intValue = value  // error: `value` is actor-isolated to `Counter` but we are in a 'MainActor'-isolated context
    view.intValue = await value // okay to asynchronously read the value
  }
}