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
如果你使用SwiftLint的'first_where'规则，并想静音交战:
UIApplication.shared.windows.first(where: { $0.isKeyWindow })
其他回答
- (UIWindow *)mainWindow {
NSEnumerator *frontToBackWindows = [UIApplication.sharedApplication.windows reverseObjectEnumerator];
for (UIWindow *window in frontToBackWindows) {
BOOL windowOnMainScreen = window.screen == UIScreen.mainScreen;
BOOL windowIsVisible = !window.hidden && window.alpha > 0;
BOOL windowLevelSupported = (window.windowLevel >= UIWindowLevelNormal);
BOOL windowKeyWindow = window.isKeyWindow;
if(windowOnMainScreen && windowIsVisible && windowLevelSupported && windowKeyWindow) {
return window;
}
}
return nil;
}
灵感来自berni的回答
let keyWindow = Array(UIApplication.shared.connectedScenes)
.compactMap { $0 as? UIWindowScene }
.flatMap { $0.windows }
.first(where: { $0.isKeyWindow })
对于Objective-C解决方案也是如此
@implementation UIWindow (iOS13)
+ (UIWindow*) keyWindow {
NSPredicate *isKeyWindow = [NSPredicate predicateWithFormat:@"isKeyWindow == YES"];
return [[[UIApplication sharedApplication] windows] filteredArrayUsingPredicate:isKeyWindow].firstObject;
}
@end
我的解决方案如下，适用于iOS 15
let window = (UIApplication.shared.connectedScenes.first as? UIWindowScene)?.windows.first
NSSet *connectedScenes = [UIApplication sharedApplication].connectedScenes;
for (UIScene *scene in connectedScenes) {
if (scene.activationState == UISceneActivationStateForegroundActive && [scene isKindOfClass:[UIWindowScene class]]) {
UIWindowScene *windowScene = (UIWindowScene *)scene;
for (UIWindow *window in windowScene.windows) {
UIViewController *viewController = window.rootViewController;
// Get the instance of your view controller
if ([viewController isKindOfClass:[YOUR_VIEW_CONTROLLER class]]) {
// Your code here...
break;
}
}
}
}
