在兴冲冲更新了Xcode11，并创建了项目之后，且发现真机和模拟器都黑屏了，怎么都不显示View了。
然后项目中比之前莫名其妙的多出来了两个文件:
20191002200056406.png
APPdelegate.m中也多了两段不明所以的代码：
#pragma mark - UISceneSession lifecycle
- (UISceneConfiguration *)application:(UIApplication *)application configurationForConnectingSceneSession:(UISceneSession *)connectingSceneSession options:(UISceneConnectionOptions *)options {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return [[UISceneConfiguration alloc] initWithName:@"Default Configuration" sessionRole:connectingSceneSession.role];
}
- (void)application:(UIApplication *)application didDiscardSceneSessions:(NSSet<UISceneSession *> *)sceneSessions {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
经查询资料得知，IOS13之后，生命周期时间就开始由UISceneDelegate接管了，一时间真的是措手不及啊，不过适应之前可以先通过以下办法恢复到原来的项目结构：
1.删除info.plist中的Application Scene Manifest
20191002200508647.png
2.删除项目中的Scenedelegate.h和Scenedelegate.m
3.删除掉APPdelegate.m中的#pragma mark - UISceneSession lifecycle代码
4.在APPdelegate.h中添加@property (strong, nonatomic) UIWindow * window;属性
