I have a UIBarButtonItem that I want to act as a logout button. When the user presses I want to popToRootViewController to take the user back to the login screen. When I call popToRootViewController nothing is happening. self.navigationController is not showing nil in print statements. I have a base view controller that all of my view controllers inherit from. I am attempting to have this logout functionality in the base view controller so all inherited view controllers don't need to also implement it. Is the fact that this is attempting to be implemented in base view controller a problem?
- (void)logoutBtnClicked {
[self.navigationController popToRootViewControllerAnimated:YES];
NSLog(#"nav: %#", self.navigationController);
}
Also, the logoutBtnClicked is being called I know.
Related
In storyboard we have great feature that allow us to make Show (e.g. push). So seems the logic is next:
If we don't have navigation controller then view controller will use present modal logic. My question is there any inverse action that I can use with Show?
I have a UIButton that close current view controller screen:
- (IBAction)onTappedCloseButton:(id)sender
{
[self.navigationController popViewControllerAnimated:YES];
}
But in case if I don't have navigation controller, how can I simple use inverse action to go back? So my solution is to check if self.navigationController is nil then use dismissing option:
[self dismissViewControllerAnimated:YES completion:nil];
But maybe there is another cool solution like Show (e.g push). But Close (e.g. pop)?
Yes, you can use an unwind segue to go back, and it will be the reverse of whatever the forward segue was.
You have two options on how to do this:
1) The Unwind segue
To make an unwind segue you have to add a method in the view controller you want to "unwind" to with the following format:
-(IBAction)someSelectorName:(UIStoryboardSegue *)sender;
You will then be able to drag from your UIButton up to the "exit" icon in your storyboard.
Wire it up to the selector you just defined and UIKit will figure out how to get back to that view controller without you having to write any code. This can be especially useful as it can figure out when it needs to call -dismissViewControllerAnimated: more than once and can call those methods successfully. It can even unwind from within a view controller embedded in a navigation controller when the view controller you're unwinding to has the navigation controller presented on top of it. (i.e. it will do a dismissViewController instead of a pop to unwind)
2) The Custom unwind method
Say you don't want to or cant trigger this action from a storyboard. There is still an option and its detailed over at this question here:
Whats the programmatic opposite of showViewController:sender:
The gist is you can write your own generic dismiss method by implementing categories on the UIKit container View controllers (or on your own container)
I have created a custom UIWebView to present a login page. I am able to get this to show by adding it as a subview. But I would like to present this modally and programatically without the use of a storyboard!
Put it in an otherwise empty view controller, and then call
[self presentViewController: animated: completion:]
in the view controller you're wanting to present it from. When you're done, you can call
[self dismissViewControllerAnimated: completion:]
to get rid of it again. This message can be sent to either the presenter or the presented view controller, though in either case it ultimately is the presenter which responds.
I have a screen in my application (login), that may be presented from any other screen
i want to put the logic of starting that screen outside of my ViewControllers, so it is not duplicated
is this possible ?
this screen may also be loaded upon an NSNotificationCenter notification message that i received
So, I'd put this into a controller where each of the view controllers calls this controller to perform the login. When the login is requested, pass the requesting view controller (or its parent if it isn't full screen) as a parameter.
Now, when the login view needs to be presented you have a generic way of presenting it from inside the 'login controller'. The requesting view controllers know nothing about the 'login controller' and the 'login controller' knows nothing about the requesting view controllers.
When triggered by a notification the app delegate can get the root view controller from the app window and pass that as the requesting view controller.
You can just create a ViewController for your login screen and give it a "storyboard id" under the "Identity inspector".
And when you'd want to show it you can instantiate it like this:
loginViewController = [[self storyboard] instantiateViewControllerWithIdentifier:#"storyboardID"];
after that you can either push it if you are using a navigationController or add it as a subview.
EDIT: how do i know if it is present:
NSArray *controllers = self.navigationController.viewControllers;
for (UIViewController* controller in controllers)
{
if ([controllers isKindOfClass:[LoginController class]])
{
NSLog(#"is already present");
}
}
In the past my app has had only 1 main view controller (MainViewController) and a login view controller (LoginViewController) but now I am moving to a Tab Bar Controller.
Before I was able to do a simple check viewDidLoad of MainViewController for the existence of a username and password in the key chain. If a username and password was not present I used a segue to pop up a modal login view controller.
With the new setup of using a Tab Bar Controller I still only have 1 view controller (MainViewController) which is the root view controller (as of now) and I am trying to do the same thing where it pops up modal of the login screen.
Now when I call the segue in the viewDidLoad of MainViewController:
[self performSegueWithIdentifier:#"loadLoginView" sender:nil];
I am getting this error:
Warning: Attempt to present <LoginViewController: 0x1757cd80> on <UITabBarController: 0x17571e50> whose view is not in the window hierarchy!
But if I associate a button to a method that loads the LoginViewController by way of a segue it works fine. I am doing that in the MainViewController like this:
-(void)loadLogin
{
[self performSegueWithIdentifier:#"loadLoginView" sender:nil];
}
I can see from the error message that when I try to perform the segue from the viewDidLoad of MainViewController it's trying to load the LoginViewController from UITabBarController.
Why can I not load the LoginViewController from the viewDidLoad of MainViewController?
Any help with this would be great.
Thanks!
It looks like -viewDidLoad is getting called before your view controller stack is added to the window. Two things you could try are:
Delaying until the next time through the run loop (this should give the view controllers time to get in place) [self performSelector:#selector(loadLogin) withObject:self afterDelay:0];. This method won't allow you to call a method with two arguments directly
You could use -presentViewController: animated: completion:. This will cause your login controller to slide in from the bottom.
I have a root view controller (RVC) that opens up a Modal ViewController (MVC). I then navigate within the MVC to few more VC's via a push. What is the best practice to get from one of those VC's back to the RVC?
Normally I have a delegate from the Modal VC that calls up to the RVC which then dismisses the modal, but if you navigate away from it, but I'm not sure how I would do that if you navigate away from it.
Without seeing any code it is a bit hard to help but let me shoot in the dark here.
I will assume that the first controller presented inside the modal view provides the protocol/delegate to call the dismiss action.
If you use UINavigationController inside your modal view to push other view controllers on the stack you can always obtain the first controller like this
UIViewController * yourFirstController = [[[self navigationController] viewControllers] objectAtIndex:0];
// and then use your delegate to call your dismiss method
// you will need to typecast your controller based on your subclass otherwise will get warning here
if ([[yourFirstController delegate] respondsToSelector:#selector(yourCloseProtocolMethod)]) {
[[yourFirstController delegate] yourCloseProtocolMethod];
}
Don't forget that a delegate doesn't have to be a property of a UIViewController inside your model navigation stack. Consider creating a singleton class that holds a reference to the rootviewcontroller as a delegate. That way any class in your application has access to it and you aren't forced to continually pass it through to every UIViewController that requires it.