从欢迎屏幕推送视图控制器时遇到问题[关闭]

Posted 2023-03-13

【中文标题】从欢迎屏幕推送视图控制器时遇到问题[关闭]

【英文标题】：Trouble pushing view controller from a welcome screen [closed]

【发布时间】：2014-02-08 19:32:55

【问题描述】：

我有一个欢迎屏幕，仅在用户第一次打开应用程序时显示。屏幕运行良好，但是当用户单击完成时，我无法让它显示正常屏幕。

这是应用程序委托中创建普通屏幕的代码 -

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

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

    if([[NSUserDefaults standardUserDefaults] boolForKey:@"TermsAccepted"]!=YES)
    
        [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"TermsAccepted"];
    

    // Override point for customization after application launch.
    FeedViewController *feedViewController = [[FeedViewController alloc] init];
    UINavigationController *nav = [[UINavigationController alloc]  initWithRootViewController:feedViewController];
    [self.window addSubview:nav.view];
    self.window.rootViewController = nav;

    [self.window makeKeyAndVisible];

    self.tabBarController = [[UITabBarController alloc] init];
    [[UITabBar appearance] setTintColor:[UIColor redColor]];


    // FeedViewController
    feedViewController=[[FeedViewController alloc] init];
    feedViewController.tabBarItem.image=[UIImage imageNamed:@"Describe-Home_Icon_NormalArtboard-1"];
    feedViewController.title = @"Timeline";
    feedViewController.tabBarItem.title = nil;

    //TodayViewController
    TodayViewController *todayViewController = [[TodayViewController alloc] init];
    todayViewController.tabBarItem.image = [UIImage imageNamed:@"Today_Icon"];
    todayViewController.title = @"Today";
    todayViewController.tabBarItem.title = nil;

    //CreateViewController
    self.createViewController = [[CreateViewController alloc] init];
    self.createViewController.tabBarItem.image = [UIImage imageNamed:@"Create_Icon"];
    self.createViewController.title = @"Create";
    self.createViewController.tabBarItem.title = nil;

    //AlertViewController
    AlertsViewController *alertsViewController = [[AlertsViewController alloc] init];
    alertsViewController.tabBarItem.image=[UIImage imageNamed:@"Alerts_IconArtboard-1"];
    alertsViewController.title=@"Alerts";
    alertsViewController.tabBarItem.title = nil;

    //ProfileViewController
    ProfileViewController *profileViewController = [[ProfileViewController alloc] init];
    profileViewController.tabBarItem.image=[UIImage imageNamed:@"Profile_IconArtboard-1"];
    profileViewController.title=@"Profile";
    profileViewController.tabBarItem.title = nil;

    NSMutableArray *tabBarViewControllers = [[NSMutableArray alloc] initWithCapacity:2];

    self.tabBarController = [[UITabBarController alloc] init];


    UINavigationController *feedNavigationController = [[UINavigationController alloc] initWithRootViewController:feedViewController];
    [tabBarViewControllers addObject:feedNavigationController];
    feedNavigationController = nil;

    UINavigationController *todayNavigationController = [[UINavigationController alloc] initWithRootViewController:todayViewController];
    [tabBarViewControllers addObject:todayNavigationController];
    todayNavigationController = nil;

    UINavigationController *createNavigationController = [[UINavigationController alloc] initWithRootViewController:self.createViewController];
    [tabBarViewControllers addObject:createNavigationController];
    createNavigationController = nil;

    UINavigationController *alertsNavigationController = [[UINavigationController alloc] initWithRootViewController:alertsViewController];
    [tabBarViewControllers addObject:alertsNavigationController];
    alertsNavigationController = nil;

    UINavigationController *profileNavigationController = [[UINavigationController alloc] initWithRootViewController:profileViewController];
    [tabBarViewControllers addObject:profileNavigationController];
    profileNavigationController = nil;

    self.tabBarController.viewControllers = tabBarViewControllers;
    tabBarViewControllers = nil;

    [self.window addSubview:self.tabBarController.view];

    return YES;

在 feedViewController 中推送欢迎视图控制器 -

if ([[NSUserDefaults standardUserDefaults] boolForKey:@"TermsAccepted"])
    NSLog(@"Second time opening the app");

else
    WelcomeViewController *welcomeViewController = [[WelcomeViewController alloc] init];
    [self.navigationController pushViewController:welcomeViewController animated:NO];

返回不起作用的提要 -

-(void)showDone:(UIButton *)sender 

    if (self.navigationItem.rightBarButtonItem.tintColor == [UIColor redColor]) 
        [[NSUserDefaults standardUserDefaults] setBool:YES forKey:@"TermsAccepted"];

        FeedViewController *feedViewController = [[FeedViewController alloc] init];
        [[UIApplication sharedApplication] keyWindow].rootViewController = feedViewController;

        self.tabBarController.tabBar.hidden = NO;
        self.navigationController.navigationBar.hidden = NO;
    

【问题讨论】：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 不是为容纳初始化应用程序所需的所有垃圾而设计的槽。

【参考方案1】：

看起来当您显示欢迎屏幕时，您将其推送到UINavigatonController。但是当您单击完成时，您会尝试在窗口上设置根视图控制器，而不是仅仅从导航控制器中弹出视图控制器。看起来您正在创建 FeedViewController 的新实例，而不是使用您已经创建的实例。

另外，您是否检查过它是否正在执行您的showDone: 方法中的代码？您正在使用== 将UIBarButtonItem 的tintColor 与UIColor 进行比较，但使用== 只会在它们都是完全相同的UIColor 实例时返回true，它们可能不会是。您需要使用方法isEqual: 来比较两种颜色，因此您可以执行以下操作：

[self.navigationItem.rightBarButtonItem.tintColor isEqual:[UIColor redColor]]

请注意，如果相同的颜色位于不同的颜色空间中，这不会总是返回 YES，但大多数时候这应该可以工作。

此外，您应该考虑将代码移出应用委托，因为通常application:didFinishLaunchingWithOptions: 仅用于需要在启动时立即完成的事情。它不应该用于初始化一堆视图控制器，它们应该只在需要显示它们时才被初始化。