iOS 13 SceneDelegate

#import "SceneDelegate.h"
#import "ViewController.h"


@interface SceneDelegate ()

@end


@implementation SceneDelegate

//当将场景添加到app中时scene(_:willConnectToSession:options:)函数会被调用的，因此这里是配置场景的最理想地方。
- (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions {

    //在iOS13后的写法
    UIWindowScene *windowScene = (UIWindowScene *)scene;
    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    [self.window setWindowScene:windowScene];
    [self.window setBackgroundColor:[UIColor whiteColor]];
    [self.window makeKeyAndVisible];
    
    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:[[ViewController alloc] init]];
    [self.window setRootViewController:nav];
}

//当场景与app断开连接是调用（注意，以后它可能被重新连接）
- (void)sceneDidDisconnect:(UIScene *)scene {
    // Called as the scene is being released by the system.
    // This occurs shortly after the scene enters the background, or when its session is discarded.
    // Release any resources associated with this scene that can be re-created the next time the scene connects.
    // The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
}

//当用户开始与场景进行交互（例如从应用切换器中选择场景）时，会调用
- (void)sceneDidBecomeActive:(UIScene *)scene {
    // Called when the scene has moved from an inactive state to an active state.
    // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
}

//当用户停止与场景交互（例如通过切换器切换到另一个场景）时调用
- (void)sceneWillResignActive:(UIScene *)scene {
    // Called when the scene will move from an active state to an inactive state.
    // This may occur due to temporary interruptions (ex. an incoming phone call).
}

//当场景变成活动窗口时调用，即从后台状态变成开始或恢复状态
- (void)sceneWillEnterForeground:(UIScene *)scene {
    // Called as the scene transitions from the background to the foreground.
    // Use this method to undo the changes made on entering the background.
}

//当场景进入后台时调用，即该应用已最小化但仍存活在后台中
- (void)sceneDidEnterBackground:(UIScene *)scene {
    // Called as the scene transitions from the foreground to the background.
    // Use this method to save data, release shared resources, and store enough scene-specific state information
    // to restore the scene back to its current state.
}

@end