On my main view in a NavigationController I have a button that brings up a new view modally to submit a post. I have a button to dismiss this view which brings the user back to the main view, however if the users proceeds to make a post, I want it to dismiss the view and proceed to a show the post in the Navigation controller.
The ideal effect would have the standard navigation controller's back button on the top that can bring the user back to the main view when they have finished looking at their post.
I have tried several different methods, but I tend to get an error stating "Warning: Attempt to present (The View I Want to Show) whose view is not in the window hierarchy!
Thanks for any info!
Yes, it's possible. This is the best way I've found to structure the app to allow this functionality.
RootViewController
UINavigationViewController
ContentViewController (your current "main" view controller)
You're basically going to create a new RootViewController that is going to contain your current UINavigationController as a child. I usually setup the window.rootViewController programmatically in the AppDelegate. I would also keep a global reference to it.
Have a look at Apple's documentation on this. Basically, the RootViewController code would look like this:
[self addChildViewController:navController];
navController.view.frame = self.view.bounds
[self.view addSubview:self.navController.view];
[navController didMoveToParentViewController:self];
Now, whenever you need to present a modal view controller, present it from the RootViewController, instead of the current/top view controller on the UINavigationBar. This allows you to manipulate the UINavigtaionController independently and you won't get the error you're seeing.
So present the modal view controller from the RootViewController, this covers the UINavigationController and its content (top view controller). Make any changes you need to the UINavigationController stack (push, pop, etc...) with no animation. When you're done dismiss the modal view controller (with animation) and it will show you're adjusted UINavigationController.
Hopefully, this all makes sense. It's kind of complex and hard to explain in text. :p
If you don't want to setup a RootViewController, you might want to try presenting the modal view controller from the UINavigationController, as that might have the same effect. From the view controller just do self.parentViewController.present.
The main thing you're trying to avoid is presenting a modal from a view controller and then removing that view controller (pop) before the modal is dismissed. The view controller that presents the view controller is responsible for dismissing it.
I finally got it all working (I'm still new to Swift) and the two comments on the question were very helpful. The most helpful of all was the top answer here's example on github.
Similar question
Related
I am presenting a view controller like this:
UINavigationController * PlacesNC = [storyboard instantiateViewControllerWithIdentifier:#"PlacesNavigationController"];
[self presentViewController:PlacesNC animated:YES completion:nil];
Once I am at the final view controller that is presented using the navigation view controller, how can I remove the initial view controller from memory?
Edit
In my application it is possible to present multiple UIViewControllers in this fashion. I will try to give a representation of what my stack might look like.
____ modal vc 5 * current view controller
____ modal vc 4
____ modal vc 3
____ modal vc 2
____ modal vc 1
____ root view controller
So if I have a stack like this, how can I remove vc 1,2,3 and maybe even 4 so that I can release the memory these other view controllers are using up? This may not be the correct to allow such a stack as this, but this is what I have now, and I just need a temporary fix as the iPhone 4 cannot handle the amount of memory used in a stack like this. So until I can come up with an alternate way to present my view controllers I just need to be able to remove some of them from the stack.
You cannot, and you don't want to. It is still in the view controller hierarchy, as I show in this diagram (DrillViewController is presented, but RootViewController is still there, "behind" it):
Presenting a view controller does not destroy the presented view controller, nor should it; if it did, you would not be able to dismiss the presented view controller and find the presenting view controller still sitting there.
Moreover, in iOS 8 it is perfectly possible to present a view controller and show the presented view controller's view in front of the presenting view controller's view, which remains visible behind it. That, for example, is how a UIAlertController presentation works. Clearly it would be a disaster if the presenting view controller ceased to exist in that situation.
Now, it may be that what you really mean is: My view controller has a property that uses a lot of memory. I don't need to hang on to that when my view controller is not frontmost. So I'd like to release it when I present another view controller. In that case, just manage the memory manually: set that property to nil on viewDidDisappear:, and recover its value (somehow) on viewWillAppear: when the presented view controller is dismissed.
One final suggestion: Perhaps the real problem is that a presented view controller was just the wrong type of hierarchical arrangement to start with. Perhaps what you really want to do is replace your original view controller in the view controller with the new view controller - because you are never coming back to it and don't need it any longer. That is perfectly possible, but of course you'll need to set up a different hierarchy architecture.
I am confused about "In which situations we have to use presentViewController and UINavigationController".
I had read so many documents, but I haven't found accurate explanation. We can always use UInavigationController then what is the use of presentViewController ?
Thanks.
UINavigationController maintains the stack of the controllers that are being viewed. So once you push through 1->2->3 view controllers then you can pop in 3->2->1 manner. Unless you don't change the stack this kind of flow is maintained by UINavigationController. Now lets say you want to show 4th view controller without disturbing the above flow. Then you can use presentViewController.
This is the simplest and basic is for using navigation controller and presentViewController
You can't push a navigation controller into other navigation controller.
You can present a navigation controller above other navigation controller.
If you push a view controller into the navigation controller, view controller's view cover only area inside navigation controller.
If you present a view controller, view controller's view cover the window hierarchy (user can't interact with other parts of the application).
You can don't use UINavigationController to present some UIViewController. You should care about "close" button to let user to close presented UIViewController
I've create test project to illustrate my answer https://github.com/K-Be/PresentTest
I've seen a lot of other questions on here about adding a UINavigationBar to a UIPopoverController. All of the examples I've seen follow one of two patterns:
In the init or viewDidLoad method of the Popover subclass, you alloc-init a UINavigationBar directly, as suggested here. This method is a little hacky, and while it shows up nicely, if the popover is a UITableViewController, you have to mess with a bunch of things to make sure the navigation bar you just added doesn't overlap one of your cells.
Alternatively, a lot of post suggest creating a UINavigationController just before presenting the popover, as shown here.
With the second method, however, won't the popover be the only controller in the newly created navigation controller? And if my view that I'm presenting the popover from is itself already in a navigation controller, the popover will NOT be in that same navigation controller, correct? It seems to be that the more appropriate thing to do would be to add the popover being created as another controller in the navigation controller that already exists (and which the controller that presents the popover is already a part of). Is that possible? Or is there a reason why the navigation controller for the popover needs to be independent from the navigation controller for the presenting controller? Or am I totally missing something here?
You have many questions, young Skywalker. :)
Creating a UINavigationController and then embedding the controller you would like to present is the way to go.
Don't get confused by all the controllers involved here:
UIPopoverController is a construct that shows an existing UIViewController in an overlay like style. UIPopoverController itself even isn't a subclass of UIViewController. The name is misleading.
So UIPopoverController hosts another controller. In your case, we let it host a UINavigationController.
UINavigationController is a subclass of UIViewController. It is a container controller and can handle a stack of UIViewControllers.
On that stack we push one UIViewController: the one you want to display and garnish with a UINavigationBar. Since Mr. UINavigationController comes with a build in UINavigationBar, he's our friend.
There is no need to subclass UIPopoverController. You just keep one static reference to it around so you can dismiss the current open popover in case you want to present another.
It does not matter where you present the UIPopoverController from. It will always be a popover. Even if presented from an existing UINavigationController. Only if you use presentViewController: you will get different results depending on the controller you're presenting from (modal or pushed on top of the stack).
won't the popover be the only controller in the newly created navigation controller?
No, the popover will contain the navigation controller and the navigation controller will only contain its root view controller (which would otherwise have been added directly to the popover as its root).
You seem to be a little confused about the relationship between the popover and the popover root view controller...
the popover will NOT be in that same navigation controller, correct
Yes, correct. The popover is effectively a window floating above all other views
Or am I totally missing something here?
Maybe... The popover would usually be used for displaying something modal, transient and smaller than full screen size. Putting a navigation controller in the popover and adding views to it is the normal approach.
Adding a navigation bar to a popover isn't hacky. A navigation bar is just another regular view. That also means that using a UITableViewController with it, the navigation bar will overlap the table view, as the UITableViewController's view property just returns the controller's tableView property. If you want to add a navigation bar above a table view, without it overlapping the table view, use a regular UIViewController and add your navigation bar and table view the normal way. UITableViewController should only be used if your only view within that view controller is a table view.
Having said that, I do agree with others that just using a navigation controller without using its navigation features is the most common approach.
I have a UIAlertView. When the user taps a button in the alert view I want to show a new UIViewController.
In order to achieve this I need to know which view controller is currently visible on screen because that particular view controller is the right one to present the new view controller.
The problem is that I have a complex hierarchy of view controllers in my app including a UINavigationController and a UITabBarController (among others). So I cannot simply use self.visibleViewController to get the currently visible view controller.
I have found a possible solution on Stackoverflow but I would like to find a neater solution without having to dig through the whole view controller stack.
UINavigationController has a property called topViewController.
Maybe it helps you.
I've looked everywhere for this, so as a last resort I figured I should ask the question.
I'm using Storyboard in XCode and have a navigation controller as my initial view. The root view of this navigation controller is a table view. In this table view, I have a button in the navigation bar that flips the view horizontally via a modal segue to a navigation controller. The root view of this controller is my map view. Now, when I want to dismiss this map view using [self dismissViewControllerAnimated:YES completion:nil] it doesn't work. It does if I take out the navigation controller. So, I'm guessing the dismissViewController is getting passed to the navigation controller, and not doing anything. I know I could implement a class for the navigation controller to handle the call and pass it on, but I don't want to do that unless absolutely necessary.
So to solve this question:
I need a way to switch between table view to map view using the flip horizontally animation and vice versa.
I need to have a navigation controller in both views, I could either be the same one, or a different one. I can't seem to find a way to use the same one, since any transitions would be pushes which don't do the flip horizontally transition.
Thanks in advance for the help!
Who is self when you call [self dismissViewControllerAnimated:YES completion:nil]?
The receiver of this message needs to be the view controller which presented the modal view controller you want to dismiss. If you call it on the presented view controller, or (in the case of container view controllers like UINavigationController, one of the view controllers it manages), UIKit will try to do the right thing but won't always succeed.
Presuming the self you refer to is the view controller containing the map view, you can get the presentingViewController property to get the object you should call dismissViewControllerAnimated:completion: on. (And if you need to get the navigation controller that's in between, use the navigationController property.)