11

我已经实现了用于状态保存的 iOS 6 API，它可以工作 - 在我退出应用程序并重新启动几毫秒后，恢复的视图控制器飞入，但随后它被我在启动时显示的主视图控制器取代。

每次应用程序启动主窗口的根视图时，我都会进行设置，所以这一定是问题所在。

这是我的代码：

- (BOOL)application:(UIApplication *)application willFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [self commonInitializationLaunching:launchOptions];
    return YES;
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [self commonInitializationLaunching:launchOptions];
    return YES;
}

- (void)commonInitializationLaunching:(NSDictionary *)launchOptions
{
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{

        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        // Override point for customization after application launch.
        static NSString *const kKeychainItemName = @"OAuthGoogleReader";
        self.viewController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil];
        self.navController = [[UINavigationController alloc] initWithRootViewController:self.viewController];

        GTMOAuth2Authentication *auth;
        auth = [GTMOAuth2ViewControllerTouch authForGoogleFromKeychainForName:kKeychainItemName
                                                                     clientID:kClientID
                                                                 clientSecret:kClientSecret];

        self.window.rootViewController = self.navController;

        [self.window makeKeyAndVisible];

        BOOL isSignedIn = [auth canAuthorize];
        if (isSignedIn) {
            NSLog(@"Signed");
        }else{
            NSString *scope = @"https://www.google.com/reader/api/";

            GTMOAuth2ViewControllerTouch *viewController;
            viewController = [[GTMOAuth2ViewControllerTouch alloc] initWithScope:scope
                                                                        clientID:kClientID
                                                                    clientSecret:kClientSecret
                                                                keychainItemName:kKeychainItemName
                                                                        delegate:self
                                                                finishedSelector:@selector(viewController:finishedWithAuth:error:)];
            [self.navController pushViewController:viewController animated:YES];
            //        self.window.rootViewController = viewController;
        }
    });
}

您可以在 -(void)commonInitializationLaunching:(NSDictionary *)launchOptions 中看到我正在设置窗口的根视图。我不知道在里面放什么。也许检查是否有保存状态然后加载此方法？但是怎么做？

谢谢！

以下是我按照 Rob 的建议尝试过的方法：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    if (!self.isRestored) {
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    }
    [self commonInitializationLaunching:launchOptions];
    [self.window makeKeyAndVisible];
    return YES;
}

什么都没有willFinishLaunching......我也从我的commonInitializationLaunching方法中删除了窗口代码。

4

2 回答 2

24

故事板将为您完成大部分繁重的工作，例如恢复窗口。但是，使用代码不会恢复窗口。您将需要使用编码器保留您的根视图控制器。您的代码将如下所示：

NSString * const AppDelegateRootVCKey = @"AppDelegateRootVCKey";

- (void)application:(UIApplication *)application willEncodeRestorableStateWithCoder:(NSCoder *)coder {
    [coder encodeObject:self.window.rootViewController forKey:AppDelegateRootVCKey];
}

- (void)application:(UIApplication *)application didDecodeRestorableStateWithCoder:(NSCoder *)coder {

    // Grabs the preserved root view controller.
    UIViewController * vc = [coder decodeObjectForKey:AppDelegateRootVCKey];

    if (vc) {
        UIWindow * window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        window.rootViewController = vc;
        window.restorationIdentifier = NSStringFromClass([window class]);

        // The green color is just to make it obvious if our view didn't load properly.
        // It can be removed when you are finished debugging.
        window.backgroundColor = [UIColor greenColor];

        self.window = window;
    }
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    if (!self.window) {

        UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

        // The blue color is just to make it obvious if our view didn't load properly.
        // It can be removed when you are finished debugging.
        window.backgroundColor = [UIColor blueColor];

        UIViewController *root = // However you create your root.

        window.rootViewController = root;
        window.restorationIdentifier = NSStringFromClass([window class]);

        self.window = window;
    }

    [self commonInitializationLaunching:launchOptions];
    [self.window makeKeyAndVisible];

    return YES;
}

另一个需要注意的问题是确保您UINavigationController的 s 和UITabBarControllers 具有恢复标识符。

于 2012-10-09T21:20:49.007 回答
6

状态恢复通常与故事板集成在一起。如果您使用情节提要，则不应创建自己的窗口、视图控制器等。您应该让情节提要为您执行此操作。正在发生的事情是情节提要正在执行所有状态恢复，然后您正在创建一个新窗口并将其放置在所有这些之上。如果是这种情况，您可能会在每次启动时创建两个 UI 副本。你只是没有注意到它。

如果您在代码中构建整个界面（不是推荐的方法，但确实有效），那么您需要在创建 UI 之前确定状态恢复是否发生。这很简单：

  • 在您的commonInitializationLaunching:, 中，仅初始化非 UI 元素（永远不会处于状态保留状态的事物）。这是处理状态恢复期间 UI 元素可能依赖的事物的地方。您当前的代码中没有任何这些。

  • 在application:didDecodeRestorableState:中，设置应用委托 ivar 以指示状态已恢复。

  • 在application:didFinishLaunchingWithOptions:，运行后commonInitializationLaunching:，检查您的 ivar。如果未恢复状态，请创建 UI。

请记住，该commonInitializationLaunching:模式的存在只是为了与 iOS 5 向后兼容。如果您不需要它，那么只需将非 UIwillFinish和 UI 放入didFinish（如果未恢复状态）。

于 2012-10-01T13:32:48.010 回答