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?
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
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
}
}
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
我为一个视图分配了一个新窗口,并设置它[newWindow makeKeyAndVisible]; 当完成使用时,设置它[newWindow resignKeyWindow]; 然后尝试通过[UIApplication sharedApplication]. keywindow直接显示原始的键-窗口。
在iOS 12上一切正常,但在iOS 13上原始的键窗口不能正常显示。它显示整个白色屏幕。
我通过以下方法解决了这个问题:
UIWindow *mainWindow = nil;
if ( @available(iOS 13.0, *) ) {
mainWindow = [UIApplication sharedApplication].windows.firstObject;
[mainWindow makeKeyWindow];
} else {
mainWindow = [UIApplication sharedApplication].keyWindow;
}
(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)
}
}
}
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
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
}
}