Hello, After upgrading to macOS 26.2, I’ve noticed a significant performance regression when calling evaluateJavaScript in an iOS App running on Mac (WKWebView, Swift project). Observed behavior On macOS 26.2, the callback of evaluateJavaScript takes around 3 seconds to return. This happens not only for: evaluateJavaScript("navigator.userAgent") but also for simple or even empty scripts, for example: evaluateJavaScript("") On previous macOS versions, the same calls typically returned in ~200 ms. Additional testing I created a new, empty Objective-C project with a WKWebView and tested the same evaluateJavaScript calls. In the Objective-C project, the callback still returns in ~200 ms, even on macOS 26.2. Question Is this a known issue or regression related to: iOS Apps on Mac, Swift + WKWebView, or behavioral changes in evaluateJavaScript on macOS 26.2? Any information about known issues, internal changes, or recommended workarounds would be greatly appreciated. Thank you. Test Code Swift class ViewController: UIViewController { private var tmpWebView: WKWebView? override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view. setupUserAgent() } func setupUserAgent() { let t1 = CACurrentMediaTime() tmpWebView = WKWebView(frame: .zero) tmpWebView?.isInspectable = true tmpWebView?.evaluateJavaScript("navigator.userAgent") { [weak self] result, error in let t2 = CACurrentMediaTime() print("[getUserAgent] \(t2 - t1)s") self?.tmpWebView = nil } } } Test Code Objective-C - (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions { NSTimeInterval startTime = [[NSDate date] timeIntervalSince1970]; WKWebView *webView = [[WKWebView alloc] init]; dispatch_async(dispatch_get_main_queue(), ^{ [webView evaluateJavaScript:@"navigator.userAgent" completionHandler:^(id result, NSError *error) { NSTimeInterval endTime = [[NSDate date] timeIntervalSince1970]; NSLog(@"[getUserAgent]: %.2f s", (endTime - startTime)); }]; }); }

In trying to convert some Objective-C to Swift, I have a subclass of NSWindowController and want to write a convenience initializer. The documentation says You can also implement an NSWindowController subclass to avoid requiring client code to get the corresponding nib’s filename and pass it to init(windowNibName:) or init(windowNibName:owner:) when instantiating the window controller. The best way to do this is to override windowNibName to return the nib’s filename and instantiate the window controller by passing nil to init(window:). My attempt to do that looks like this: class EdgeTab: NSWindowController { override var windowNibName: NSNib.Name? { "EdgeTab" } required init?(coder: NSCoder) { super.init(coder: coder) } convenience init() { self.init( window: nil ) } } But I'm getting an error message saying "Incorrect argument label in call (have 'window:', expected 'coder:')". Why the heck is the compiler trying to use init(coder:) instead of init(window:)?