How to call a View Controller programmatically?

问题:

I have looked at all the tutorials I can find on this one, and I still don't have the answer. I need to call another view from the code. I am using UIStoryboards. I have changed the view many times by control-dragging from UIButtons, but now it must be from the code. I am trying to call the info page from the main menu if it is the first time the user has opened the app. I cannot seem to find a way to change the views from the code, however. All my views are controlled by the same files (ViewController2). The identifier of my main menu is ViewControllerMain, and the identifier of the info page is ViewControllerInfo. First I tried this:

[ViewControllerMain presentViewController: ViewControllerInfo 
                                 animated:YES 
                               completion: NULL];

Then I tried making different UIViewControllers for each and saying:

[ViewController2 presentViewController: ViewController 
                              animated:YES 
                            completion: NULL];

Neither worked. For the first one, it says:

Use of undeclared identifier ViewControllerMain.

In the second one, it says:

unexpected interface name 'ViewController': expected identifier.

What can I do?

回答1:

To create a view controller:

UIViewController * vc = [[UIViewController alloc] init];

To call a view controller (must be called from within another viewcontroller):

[self presentViewController:vc animated:YES completion:nil];

For one, use nil rather than null.

---

Loading a view controller from the storyboard:

NSString * storyboardName = @"MainStoryboard"; 
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:storyboardName bundle: nil];
UIViewController * vc = [storyboard instantiateViewControllerWithIdentifier:@"IDENTIFIER_OF_YOUR_VIEWCONTROLLER"];
[self presentViewController:vc animated:YES completion:nil];

Identifier of your view controller is either equal to the class name of your view controller, or a Storyboard ID that you can assign in the identity inspector of your storyboard.

回答2:

You need to instantiate the view controller from the storyboard and then show it:

ViewControllerInfo* infoController = [self.storyboard instantiateViewControllerWithIdentifier:@"ViewControllerInfo"];
[self.navigationController pushViewController:infoController animated:YES];

This example assumes that you have a navigation controller in order to return to the previous view. You can of course also use presentViewController:animated:completion:. The main point is to have your storyboard instantiate your target view controller using the target view controller's ID.

回答3:

Swift

This gets a view controller from the storyboard and presents it.

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let secondViewController = storyboard.instantiateViewController(withIdentifier: "secondViewControllerId") as! SecondViewController
self.present(secondViewController, animated: true, completion: nil)

Change the storyboard name, view controller name, and view controller id as appropriate.

回答4:

You can call ViewController this way, If you want with NavigationController

1.In current Screen : Load new screen

VerifyExpViewController *addProjectViewController = [[VerifyExpViewController alloc] init];
[self.navigationController pushViewController:addProjectViewController animated:YES];

2.1 In Loaded View : add below in .h file

@interface VerifyExpViewController : UIViewController <UINavigationControllerDelegate>

2.2 In Loaded View : add below in .m file

  @implementation VerifyExpViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.navigationController.delegate = self;
    [self setNavigationBar];
}
-(void)setNavigationBar
{
    self.navigationController.navigationBar.backgroundColor = [UIColor clearColor];
    self.navigationController.navigationBar.translucent = YES;
    [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"B_topbar.png"] forBarMetrics:UIBarMetricsDefault];
    self.navigationController.navigationBar.titleTextAttributes = @{NSForegroundColorAttributeName: [UIColor whiteColor]};
    self.navigationItem.hidesBackButton = YES;
    self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"Btn_topback.png"] style:UIBarButtonItemStylePlain target:self action:@selector(onBackButtonTap:)];
    self.navigationItem.leftBarButtonItem.tintColor = [UIColor lightGrayColor];
    self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"Save.png"] style:UIBarButtonItemStylePlain target:self action:@selector(onSaveButtonTap:)];
    self.navigationItem.rightBarButtonItem.tintColor = [UIColor lightGrayColor];
}

-(void)onBackButtonTap:(id)sender
{
    [self.navigationController popViewControllerAnimated:YES];
}
-(IBAction)onSaveButtonTap:(id)sender
{
    //todo for save button
}

@end

Hope this will be useful for someone there :)

回答5:

There's 2 ways you can do this:

1, Create a segue to your ViewController in your Storyboard as explained in my answer here: How to perform a segue that is not related to user input in iOS 5?

2, Give your ViewController and identifier and call it using the code in my answer here: Call storyboard scene programmatically (without needing segue)?

回答6:

main logic behind this is_,

NSString * storyboardIdentifier = @"SecondStoryBoard";

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:storyboardIdentifier bundle: nil];

UIViewController * UIVC = [storyboard instantiateViewControllerWithIdentifier:@"YourviewControllerIdentifer"];

[self presentViewController:UIVC animated:YES completion:nil];

回答7:

Import the view controller class which you want to show and use the following code

KartViewController *viewKart = [[KartViewController alloc]initWithNibName:@"KartViewController" bundle:nil];
[self presentViewController:viewKart animated:YES completion:nil];

回答8:

        UIStoryboard* storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard_iPhone_iOS7" bundle:nil];
            AccountViewController * controller = [storyboard instantiateViewControllerWithIdentifier:@"accountView"];
            //            [self presentViewController:controller animated:YES completion:nil];

        UIViewController *topRootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
        while (topRootViewController.presentedViewController)
        {
            topRootViewController = topRootViewController.presentedViewController;
        }

        [topRootViewController presentViewController:controller animated:YES completion:nil];