我使用核心数据与云工具包，因此要检查iCloud用户状态在应用程序启动。如果出现问题，我想向用户发出一个对话框，我使用UIApplication.shared.keyWindow?. rootviewcontroller ?.present(…)到目前为止。
在Xcode 11 beta 4中，现在有一个新的弃用消息，告诉我:
'keyWindow'在iOS 13.0中已弃用:不应该用于支持多个场景的应用程序，因为它在所有连接的场景中返回一个键窗口
我应该如何呈现对话呢?
当前回答
通常使用
斯威夫特5
UIApplication.shared.windows.filter {$0.isKeyWindow}.first
另外，在UIViewController中:
self.view.window
视图。窗口是当前场景的窗口
WWDC 2019:
关键的窗口 手动跟踪窗口
在iPad上介绍多个Windows - WWDC 2019 -视频-苹果开发人员 支持iPad上的多个Windows |苹果开发者文档
其他回答
我的解决方案如下，适用于iOS 15
let window = (UIApplication.shared.connectedScenes.first as? UIWindowScene)?.windows.first
如果你使用SwiftLint的'first_where'规则，并想静音交战:
UIApplication.shared.windows.first(where: { $0.isKeyWindow })
这是我的解决方案:
let keyWindow = UIApplication.shared.connectedScenes
.filter({$0.activationState == .foregroundActive})
.compactMap({$0 as? UIWindowScene})
.first?.windows
.filter({$0.isKeyWindow}).first
使用如:
keyWindow?.endEditing(true)
(在运行于Xcode 13.2.1的iOS 15.2上测试)
extension UIApplication {
var keyWindow: UIWindow? {
// Get connected scenes
return UIApplication.shared.connectedScenes
// Keep only active scenes, onscreen and visible to the user
.filter { $0.activationState == .foregroundActive }
// Keep only the first `UIWindowScene`
.first(where: { $0 is UIWindowScene })
// Get its associated windows
.flatMap({ $0 as? UIWindowScene })?.windows
// Finally, keep only the key window
.first(where: \.isKeyWindow)
}
}
如果你想在关键的UIWindow中找到呈现的UIViewController，这是另一个你可以发现有用的扩展:
extension UIApplication {
var keyWindowPresentedController: UIViewController? {
var viewController = self.keyWindow?.rootViewController
// If root `UIViewController` is a `UITabBarController`
if let presentedController = viewController as? UITabBarController {
// Move to selected `UIViewController`
viewController = presentedController.selectedViewController
}
// Go deeper to find the last presented `UIViewController`
while let presentedController = viewController?.presentedViewController {
// If root `UIViewController` is a `UITabBarController`
if let presentedController = presentedController as? UITabBarController {
// Move to selected `UIViewController`
viewController = presentedController.selectedViewController
} else {
// Otherwise, go deeper
viewController = presentedController
}
}
return viewController
}
}
你可以把它放在任何你想要的地方，但我个人把它作为UIViewController的扩展。
这让我可以添加更多有用的扩展，比如更容易地呈现UIViewControllers:
extension UIViewController {
func presentInKeyWindow(animated: Bool = true, completion: (() -> Void)? = nil) {
DispatchQueue.main.async {
UIApplication.shared.keyWindow?.rootViewController?
.present(self, animated: animated, completion: completion)
}
}
func presentInKeyWindowPresentedController(animated: Bool = true, completion: (() -> Void)? = nil) {
DispatchQueue.main.async {
UIApplication.shared.keyWindowPresentedController?
.present(self, animated: animated, completion: completion)
}
}
}
我已经解决了:
let scenes = UIApplication.shared.connectedScenes
let windowScene = scenes.first as? UIWindowScene
let window = windowScene?.windows.first
