Berni的代码很好，但它不工作时，应用程序从后台回来。

这是我的代码:

class var safeArea : UIEdgeInsets
{
    if #available(iOS 13, *) {
        var keyWindow = UIApplication.shared.connectedScenes
                .filter({$0.activationState == .foregroundActive})
                .map({$0 as? UIWindowScene})
                .compactMap({$0})
                .first?.windows
                .filter({$0.isKeyWindow}).first
        // <FIX> the above code doesn't work if the app comes back from background!
        if (keyWindow == nil) {
            keyWindow = UIApplication.shared.windows.first { $0.isKeyWindow }
        }
        return keyWindow?.safeAreaInsets ?? UIEdgeInsets()
    }
    else {
        guard let keyWindow = UIApplication.shared.keyWindow else { return UIEdgeInsets() }
        return keyWindow.safeAreaInsets
    }
}

由于许多开发人员要求将Objective C代码的这种弃用进行替换。您可以使用下面的代码来使用keyWindow。

+(UIWindow*)keyWindow {
    UIWindow        *windowRoot = nil;
    NSArray         *windows = [[UIApplication sharedApplication]windows];
    for (UIWindow   *window in windows) {
        if (window.isKeyWindow) {
            windowRoot = window;
            break;
        }
    }
    return windowRoot;
}

我在AppDelegate类中创建并添加了这个方法作为类方法，并以下面的非常简单的方式使用它。

[AppDelegate keyWindow];

不要忘记像下面这样在AppDelegate.h类中添加这个方法。

+(UIWindow*)keyWindow;

您可能知道，由于可能存在多个场景，因此不建议使用键窗口。最方便的解决方案是提供一个currentWindow作为扩展，然后进行搜索和替换。

extension UIApplication {
    var currentWindow: UIWindow? {
        connectedScenes
            .compactMap { $0 as? UIWindowScene }
            .flatMap { $0.windows }
            .first { $0.isKeyWindow }
    }
}

当.foregroundActive场景为空时，我遇到了这个问题

这是我的变通办法

public extension UIWindow {
    @objc
    static var main: UIWindow {
        // Here we sort all the scenes in order to work around the case
        // when no .foregroundActive scenes available and we need to look through
        // all connectedScenes in order to find the most suitable one
        let connectedScenes = UIApplication.shared.connectedScenes
            .sorted { lhs, rhs in
                let lhs = lhs.activationState
                let rhs = rhs.activationState
                switch lhs {
                case .foregroundActive:
                    return true
                case .foregroundInactive:
                    return rhs == .background || rhs == .unattached
                case .background:
                    return rhs == .unattached
                case .unattached:
                    return false
                @unknown default:
                    return false
                }
            }
            .compactMap { $0 as? UIWindowScene }

        guard connectedScenes.isEmpty == false else {
            fatalError("Connected scenes is empty")
        }
        let mainWindow = connectedScenes
            .flatMap { $0.windows }
            .first(where: \.isKeyWindow)

        guard let window = mainWindow else {
            fatalError("Couldn't get main window")
        }
        return window
    }
}

我已经解决了:

let scenes = UIApplication.shared.connectedScenes
let windowScene = scenes.first as? UIWindowScene
let window = windowScene?.windows.first

一个UIApplication扩展:

extension UIApplication {

    /// The app's key window taking into consideration apps that support multiple scenes.
    var keyWindowInConnectedScenes: UIWindow? {
        return windows.first(where: { $0.isKeyWindow })
    }

}

用法:

let myKeyWindow: UIWindow? = UIApplication.shared.keyWindowInConnectedScenes