I am working on some old code that I didn't write, and it's really not architected well...
The situation is that a view controller presents a custom view controller modally, however every 30 seconds the presenting view controller is recreated.
The issue here is that if the modal is on screen when this happens, then any effort to dismiss it results in odd behaviour (such as a white screen).
I have tried calling [self.presentedViewController dismissViewControllerAnimated]; on the newly recreated controller, but presentedViewController is nil as you would expect.
I have also tried keeping a weak reference to the modal view controller, then when the presenting VC is reloaded, setting this value to that of the old VC. This has allowed me to call self.customModalVC dismissViewControllerAnimated]; but this is causing the aforementioned white screen, perhaps because it's presenting VC is no longer in the stack?
Any and all suggestions appreciated.
Try passing the navigation controller to newly presented ViewController:
presentedVC.navigation = self.navigationController
Add this to newly created one for dismissing
self.dismiss(animated: false) {
_ = self.navigation?.popViewController(animated: true)
}
Related
I have a bunch of views and then a logout button, which logs the user out and takes them to the first view controller (a login/register screen). I tried doing this with a modal presentation, but it destroys my navigation, and I can't use a pop to root view controller because it is not the root view controller - I am at least 2 navigation controllers deep. How would I go about somehow displaying only the first one? I basically need it to act as if the app was just relaunched. Would unwind segues help in some way? Thanksthis is what I mean by messing up the navigation. The following view controllers now pop up, instead of (the following pic is from the actual first time launching the app) how it should look
Supposing that you use a UINavigationController, you can use the UINavigationController.setViewControllers(_:animated:) method in combination with UINavigationController.viewControllers. The latter provides you an array of view controllers in the exact order they are stacked by the navigation controller, while the former can be used to alter the navigation stack. For instance, if you want to keep only the first 3 view controllers in the navigation stack:
guard let navigationController = self.navigationController else { return }
let viewControllersToKeep = navigationController.viewControllers.prefix(3)
navigationController.setViewControllers(viewControllersToKeep, animated: true)
Note: The animation performed by the navigation controller in this case is usually (I believe always, but not 100% sure) a push animation instead of pop, which might not be the desired one.
So if you want to make the navigation controller to perform a pop animation, then you should call pop until you reach the desired view controller, but the key is to animated a single pop. For the same example as above:
guard let navigationController = self.navigationController else { return }
let numberOfPops = navigationController.viewControllers.count - 3
for i in 0..<numberOfPops {
let animated = i == 0
navigationController.popViewController(animated: animated)
}
Hope this answers the question about popping to the desired view controller (you can detect your view controller by its type, then you can find out its index and use the logic above).
If you want to dismiss to the first presenting view controller, then you need to call UIViewController.dismiss(animated:completion:) on the first presenting view controller. dismiss method will behaves like this:
If the view controller is presenting a view controller, then it will dismiss the presented view controller;
If the view controller is not presenting any view controller, but it is presented by another view controller (i.e. has a parent view controller), then it will ask the parent view controller to dismiss it;
If none of the above, it will do nothing.
So long story short, you need to call dismiss on the view controller that you want to be left on the screen.
I basically need it to act as if the app was just relaunched.
In this case, assigning the login/register screen controller to UIWindow.rootViewController seems to be the right option. This topic has been already covered here: Swift ios set a new root view controller
I have a basic scenario:
I present a VC modally using self.present(, animated:, completion:).
Sometimes due to interactions in this modal VC i need to close one modal and open another one.
So i do the following:
weak var presenter = self.presentingViewController
let newVc = UIViewController()
presenter?.dismiss(animated: true, completion: {
presenter?.present(newVc, animated: true, completion: nil)
})
This works but there is the annoying delay when switching the VC's when user sees the original presenter and can try to interact with it (to open other modals...).
I tried setting animated: false but that doesn't seem to work :/
I can't really switch to UINavigationController model for this because the modals i am presenting themselves are Page View Controllers and have the whole hierarchy of dependent views; the user is never going 'back'; so i'd really like to just present the new modal as quickly as possible...
Update My question is not about how to control or choose the animation. My questions is about having no delay between the modals.
The built-in view controller architecture that switches views with no transition is the tab bar controller. So just turn your view controller into a tab bar controller — with no visible tab bar! To change to the other view controller just change tabs (in code). The change is instant.
This screencast makes it clear that this works as described. We present a view controller (yellow). Then we switch back and forth between two view controllers (green and yellow) as the presented view controllers, instantly. Finally, we dismiss whichever one (green or yellow) is showing. I'm doing it all with simple buttons but that's just for the demo; obviously you could do this however you like. It's the architecture that's the important thing.
I can think only of solutions which would require you to handle the animations yourself
create custom modal transition using UIViewControllerTransitionCoordinator
add your controllers to container views as suggested by #muhammed-gül
present newVC over self and dismiss all presented controllers when you're done
And just a tip, you don't always need to wait for the dismiss completion closure, you can call this and it usually works, but still the underlying viewController is visible.
dismiss(animated: true)
present(newVC, animated: true)
I am trying to achieve a navigation similar to the Netflix app for iOS. When you click on a movie, a modal window pops up with a close button. If within this movie I choose to see another movie then the second modal pops up and in addition to the close button, a back button appears. I can use the back button to dismiss one by one and the close button to return to the base screen.
I am able to dismiss a single view using
dismiss(animated: true, completion: nil)
but how can I return to the base screen closing all modals at once? Also, is modals the way to go? I chose this because I didn't want the navigation bar on top.
I'm working with Swift 4.2 in Xcode 10.
The way you are dismissing a ViewController is not the correct way. The presenting view controller is responsible for dismissing the view controller. Ideally you have to implement a protocol in your presenting ViewController and , dismiss your modal from your 'presenting' ViewController not 'presented' ViewController.
The reason why your way still works is, when a ViewController calls self.dimiss if there's nothing to dismiss UIKit will delegate it back to its parent. If you implement this correct way, once you dismiss , your presenting viewcontroller will dismiss , hence all the presented viewcontrollers will be dismissed instead of the last one.
From Apple Docs:
The presenting view controller is responsible for dismissing the view controller it presented. If you call this method on the presented view controller itself, UIKit asks the presenting view controller to handle the dismissal.
If you present several view controllers in succession, thus building a stack of presented view controllers, calling this method on a view controller lower in the stack dismisses its immediate child view controller and all view controllers above that child on the stack. When this happens, only the top-most view is dismissed in an animated fashion; any intermediate view controllers are simply removed from the stack. The top-most view is dismissed using its modal transition style, which may differ from the styles used by other view controllers lower in the stack.
If you want to retain a reference to the view controller's presented view controller, get the value in the presentedViewController property before calling this method.
The completion handler is called after the viewDidDisappear(_:) method is called on the presented view controller.
try this
self.navigationController?.viewControllers.removeAll(where: {$0.isModalInPopover})
I was wondering if self.navigationController?.popViewController(animated: true) actually dismisses the View Controller it is being called on or if it just returns to the previous? If so, does this mean that I must manually dismiss the View Controller along with using the above code? Thanks.
When you pop a view controller off a UINavigationController's navigation stack, the UINavigationController releases the popped view controller and by default it goes out of existence. You can see this by implementing that view controller's deinit.
If you don't see deinit called, then that view controller is leaking because you have a retain cycle, and you need to worry about why that is.
I have a UIImagePickerController presented on screen. When I choose the photo I need to dismiss the PickerController then immediately present another PhotoEditController. Here is my code
picker.dismissViewControllerAnimated(false, completion: {
self.presentViewController(editPhotoVC, animated: false, completion: nil)
})
There is a 0.1s flash between dismissing old VC and presenting new VC so the presentingViewController (self) is shown. How do I avoid that in an elegant solution not hacking it through? Thanks
The standard way of implementation is to dismiss first view controller (VC) with animation and present second VC with animation.
However, depending on your view hierarchy, you could also have your second VC loaded first and then present first VC on top of it. With this simply dismissing first VC without animation should show underneath second VC without delay.
Third approach, as LLooggaann suggested, don't dismiss first VC and simply present second VC. Once done, dismiss the entire view controller hierarchy in one shot.
You could instantiate PhotoEditController's instance, then do something like this:
instance.willMoveToParentViewController(controllerThatPresentsPicker)
controllerThatPresentsPicker.addChildViewController(instance)
controllerThatPresentsPicker.view.insertSubview(instance.view, belowSubview: picker.view)
instance.didMoveToParentViewController(controllerThatPresentsPicker)
It looks a bit like a hack though
That is most probably because dismiss is sent to the VC that presented the picker and it dismisses the picker modal vc and executes the completion handler after attempting to present the parent VC which is itself.
one solution would be creating your own transition class, you can basically copy paste the code from here to do that