導航欄按鈕在加載相應視圖之前加載隨機視圖

Question

如果用戶點擊我創建的後退按鈕，我的回答視圖控制器（顯示答案的視圖控制器）上有一個後退按鈕切換到視圖的標題爲「返回」，只是一個空的桌面視圖，然後切換回我的主要視圖，顯示所有需要回答的問題。這是爲什麼發生？它是一個非常簡短的事情，但絕對明顯！

UINavigationBar *navBar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 48)]; 
navBar.delegate = self; 
UINavigationItem *backItem = [[UINavigationItem alloc] initWithTitle:@"Back"]; 
[navBar pushNavigationItem:backItem animated:NO]; 

UINavigationItem *topItem = [[UINavigationItem alloc] initWithTitle:@"Question"]; 
[navBar pushNavigationItem:topItem animated:NO]; 
topItem.leftBarButtonItem = nil; 

[self.view addSubview:navBar]; 


- (BOOL)navigationBar:(UINavigationBar *)navigationBar shouldPopItem:(UINavigationItem *)item 
{ 

    ViewController *controller = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil]; 
    controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; 
    [self presentViewController:controller animated:YES completion:nil]; 
    return true; 
} 

- (void)navigationBar:(UINavigationBar *)navigationBar didPopItem:(UINavigationItem *)item 
{ 

    ViewController *controller = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil]; 
    controller.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal; 
    [self presentViewController:controller animated:YES completion:nil]; 
} 

Answer 1

你創建自己的UINavigationBar和UINavigationItem情況下，你可能不應該。您所描述的情況正是UINavigationController的用途。當使用UINavigationController時，它會創建您在屏幕上顯示的UINavigationBar和每個UIViewController（推入導航控制器）都有其自己的UINavigationItem（標題取自視圖控制器的title）。

你題爲「回到」空「觀點」的原因是，你創造它：

UINavigationItem *backItem = [[UINavigationItem alloc] initWithTitle:@"Back"]; 
[navBar pushNavigationItem:backItem animated:NO]; 

省卻了這一切，創造UINavigationController，使你的問題的視圖控制器它的根視圖控制器，然後將導航控制器添加到屏幕。然後，當回答問題時，請按下回答視圖控制器：

[self.navigationController pushViewController:answerViewController animated:YES];