Ios UIWindow rootViewController找不到UIViewController子类

我有一个CSRootViewController:UIViewController没有xib文件，一个CSFirstViewController:CSRootViewController有xib文件。对于以下代码，我将得到错误：

应用程序窗口应在以下位置具有根视图控制器： 应用程序启动的结束

使现代化 这是CSFirstViewController的代码。h文件：

@interface CSFirstViewController : CSRootViewController

@end

和.m文件

@interface CSFirstViewController ()

- (IBAction)pushButtonClicked:(id)sender;

@end

@implementation CSFirstViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - IBAction methods

- (IBAction)pushButtonClicked:(id)sender
{
    CSSecondViewController *secondVC = [[CSSecondViewController alloc] init];
    [self.rootViewController pushCSViewController:secondVC animated:YES];
}

@end

---

有人能告诉我原因吗？

我找到了解决问题的方法。只需添加[self.windowaddsubview:firstViewController.view]；在设置窗口的rootViewController之后。但我仍然不知道为什么会发生这种情况。

请将CSFirstViewController.h和.m类放在日志中……您应该记录firstViewController以查看它是否为零。我在这段代码中看不到任何会导致您看到的问题的其他内容。除非您重载了CSFirstViewController init方法，否则您应该使用UIViewController的initWithNibName:bundle:method来使用xib文件初始化根控制器。@V.J.现在添加了您要查看的代码。@rdelmar我已经检查过了，它不是nil。

@interface CSFirstViewController ()

- (IBAction)pushButtonClicked:(id)sender;

@end

@implementation CSFirstViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - IBAction methods

- (IBAction)pushButtonClicked:(id)sender
{
    CSSecondViewController *secondVC = [[CSSecondViewController alloc] init];
    [self.rootViewController pushCSViewController:secondVC animated:YES];
}

@end