XCode Preview Error: "Replaced Accessor for 'keyWindow'"

Question

Adding the some code to one of my files in XCode causes the following error to show when trying to run previews for that file:

Compiling failed: replaced accessor for 'keyWindow' occurs in multiple places.

The error only happens when the following code is used in the file:

extension UIApplication {
    
    var keyWindow: UIWindow? {
        return UIApplication.shared.connectedScenes
            .filter { $0.activationState == .foregroundActive }
            .first(where: { $0 is UIWindowScene })
            .flatMap({ $0 as? UIWindowScene })?.windows
            .first(where: \.isKeyWindow)
    }
    
    var keyWindowPresentedController: UIViewController? {
        var viewController = self.keyWindow?.rootViewController
        
        if let presentedController = viewController as? UITabBarController {
            viewController = presentedController.selectedViewController
        }
        
        while let presentedController = viewController?.presentedViewController {
            if let presentedController = presentedController as? UITabBarController {
                viewController = presentedController.selectedViewController
            } else {
                viewController = presentedController
            }
        }
        return viewController
    }
}

I know very little about UIKit, and this code was copy/pasted from online. Why is this code crashing my preview, and how can I fix it?

I'm running XCode 13.4.1 on macOS Monterey

score 2 · Accepted Answer · answered Jun 22 '22 at 05:28

UIApplication already has keyWindow property and it seems there is already other extension with same property in workspace, so just use different name for your, like

extension UIApplication {
    
    var currentWindow: UIWindow? {

*or find which one another is and see if you can reuse it.

XCode Preview Error: "Replaced Accessor for 'keyWindow'"

1 Answers1