CallViewController无法present出来，实时语音没法实现

这是ChatHelprDemo中执行的present断点




这是我写的DCMainBarViewController

@interface DCMainBarViewController ()

@property (nonatomic, strong) UINavigationController *navigationController;

@property (nonatomic, strong) WXTabBarController *tabBarController;

@end



@implementation DCMainBarViewController



- (void)viewDidAppear:(BOOL)animated

{

    [super viewDidAppear:animated];

    

    UIWindow *window = [[UIApplication sharedApplication].windows objectAtIndex:0];

    window.rootViewController = self.navigationController;

}



- (UINavigationController *)navigationController {

    if (_navigationController == nil) {

        UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:self.tabBarController];

//        navigationController.navigationBar.tintColor = [UIColor colorWithRed:26 / 255.0 green:178 / 255.0 blue:10 / 255.0 alpha:1];

        _navigationController = navigationController;

    }

    return _navigationController;

}



- (WXTabBarController *)tabBarController {

    if (_tabBarController == nil) {

        WXTabBarController *tabBarController = [[WXTabBarController alloc] init];

        

        DCHomePageViewController *mainframeViewController = ({

            DCHomePageViewController *mainframeViewController = [[DCHomePageViewController alloc]initWithNibName:@"DCHomePageViewController" bundle:nil];

            

            UIImage *mainframeImage   = [UIImage imageNamed:@"tab_bar_home"];

            UIImage *mainframeHLImage = [UIImage imageNamed:@"tab_bar_home_press"];

            

//            mainframeViewController.title = @"首页";

            mainframeViewController.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"首页" image:mainframeImage selectedImage:mainframeHLImage];

//            mainframeViewController.view.backgroundColor = [UIColor colorWithRed:48 / 255.0 green:67 / 255.0 blue:78 / 255.0 alpha:1];

            mainframeViewController.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"barbuttonicon_add"]

                                                                                                         style:UIBarButtonItemStylePlain

                                                                                                        target:self

                                                                                                        action:@selector(didClickAddButton:)];

            

            mainframeViewController;

        });

        

        ConversationListController *contactsViewController = ({

            ConversationListController *contactsViewController = [[ConversationListController alloc] init];

            

            UIImage *contactsImage   = [UIImage imageNamed:@"tab_bar_huihua"];

            UIImage *contactsHLImage = [UIImage imageNamed:@"tab_bar_huihua_press"];

            

//            contactsViewController.title = @"会话";

            contactsViewController.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"会话" image:contactsImage selectedImage:contactsHLImage];

//            contactsViewController.view.backgroundColor = [UIColor colorWithRed:115 / 255.0 green:155 / 255.0 blue:6 / 255.0 alpha:1];

            

            contactsViewController;

        });

        UIStoryboard * storyBoard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];

        DCQuanZiViewController *meViewController = ({

            DCQuanZiViewController *meViewController = [storyBoard instantiateViewControllerWithIdentifier:@"quanziViewC"];

            

            UIImage *meImage   = [UIImage imageNamed:@"tab_bar_quanzi"];

            UIImage *meHLImage = [UIImage imageNamed:@"tab_bar_quanzi_press"];

            

            meViewController.title = @"工作圈";

            meViewController.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"工作圈" image:meImage selectedImage:meHLImage];

//            meViewController.view.backgroundColor = [UIColor colorWithRed:199 / 255.0 green:135 / 255.0 blue:56 / 255.0 alpha:1];

            

            meViewController;

        });



        

        DCApplicationViewController *discoverViewController = ({

            DCApplicationViewController *discoverViewController = [[DCApplicationViewController alloc]initWithNibName:@"DCApplicationViewController" bundle:nil];

            

            UIImage *discoverImage   = [UIImage imageNamed:@"tab_bar_app"];

            UIImage *discoverHLImage = [UIImage imageNamed:@"tab_bar_app_press"];

            

//            discoverViewController.title = @"应用";

            discoverViewController.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"应用" image:discoverImage selectedImage:discoverHLImage];

//            discoverViewController.view.backgroundColor = [UIColor colorWithRed:32 / 255.0 green:85 / 255.0 blue:128 / 255.0 alpha:1];

            

            discoverViewController;

        });

        

        UIStoryboard * storyBoard1 = [UIStoryboard storyboardWithName:@"Main" bundle:nil];

            DCNewSettingViewController *settingViewC=[storyBoard1 instantiateViewControllerWithIdentifier:@"newSettingViewC"];

        DCNewSettingViewController*NewSettingcoverViewController = ({

            DCNewSettingViewController *NewSettingcoverViewController = [storyBoard1 instantiateViewControllerWithIdentifier:@"newSettingViewC"];

            

            UIImage *discoverImage   = [UIImage imageNamed:@"tab_bar_personal"];

            UIImage *discoverHLImage = [UIImage imageNamed:@"tab_bar_personal_press"];

            

//            NewSettingcoverViewController.title = @"设置";

            NewSettingcoverViewController.tabBarItem = [[UITabBarItem alloc] initWithTitle:@"设置" image:discoverImage selectedImage:discoverHLImage];

//            NewSettingcoverViewController.view.backgroundColor = [UIColor colorWithRed:32 / 255.0 green:85 / 255.0 blue:128 / 255.0 alpha:1];

            

            NewSettingcoverViewController;

        });

        

        tabBarController.title = @"首页";

//        tabBarController.tabBar.tintColor = [UIColor colorWithRed:26 / 255.0 green:178 / 255.0 blue:10 / 255.0 alpha:1];

//        

        tabBarController.viewControllers = @[

                                             [[UINavigationController alloc] initWithRootViewController:mainframeViewController],

                                             [[UINavigationController alloc] initWithRootViewController:contactsViewController],

                                             [[UINavigationController alloc] initWithRootViewController:meViewController],

                                             [[UINavigationController alloc] initWithRootViewController:discoverViewController],

                                             [[UINavigationController alloc] initWithRootViewController:NewSettingcoverViewController]

                                             ];



        

        

        

        _tabBarController = tabBarController;

    }

    return _tabBarController;

}

尝试去alloc init，但我的mainVC依旧空的，是什么原因导致的？怎么能够解决？，present不出来callViewController界面是mainVC为空导致的吗？