视图push和presentViewController注意点

- (void)publishClick{
    
    NSLog(@"发布按钮被点击");
    PublishViewController *publishVc = [[PublishViewController alloc]init];
    // 包装创建导航控制器
    MainNavigationController *nav = [[MainNavigationController alloc]initWithRootViewController:publishVc];
    
    // 这里不能使用self来弹出其他控制器, 因为self执行了dismiss操作
    UIViewController *root = [UIApplication sharedApplication].keyWindow.rootViewController;
    [root presentViewController:nav animated:YES completion:nil];
    
}

 // 在视图中push,需要取到导航控制器

    // 先取得TabBarViewController
    UITabBarController *tabBarVc = (UITabBarController *)[UIApplication sharedApplication].keyWindow.rootViewController;
    // 再取得导航控制器

// 以下一条语句:This may return the "More" navigation controller if it exists.

    UINavigationController *nav = (UINavigationController *)tabBarVc.selectedViewController; 

    [nav pushViewController:webVc animated:YES];