Swift after dismiss Current ViewController then the Presenting ViewController not calling viewWillAppear() - ios

In my case, I am using two view controller VC1 and VC2. Here, VC1 button click to Present Modally and Over Full Screen presentation with Cross Dissolve Transition to presenting VC2. Now, from VC2 dismiss then I didn’t get call VC1 viewWillAppear().
I am not using code base for Present model. I am using Storyboard Segue.
Why it happening and how to fix this?

From Docs,
Note
If a view controller is presented by a view controller inside of a
popover, this method is not invoked on the presenting view controller
after the presented controller is dismissed.
So according to the documentation when a ViewController presents another ViewController modally this method will not be called. To fix this you need to use
func dismiss(animated flag: Bool,
completion: (() -> Void)? = nil)
and move(or repeat) some of viewWillLoad logic to completion handler.

Change presentation to Full screen or If you want to stick to Over Full Screen then make vc2 delegate of vc1 and call delegate method on dismiss.
To understand the concept you can refer to : https://medium.com/livefront/why-isnt-viewwillappear-getting-called-d02417b00396

Related

How to update view behind the popover view on dismissal of the popover?

I have a View and a popover that appears on top of it, which alters data. I am trying to update the view/run a function on the main view (that is under the popover) once the popover is dismissed. I have tried numerous things including viewwillappear, but it isn't being registered as technically the view doesn't disappear since the popover is just above (And you can see part of the view from behind). If anyone can suggest how to call a function on the parent view when dismissing the popover (without crashing the app, as most of my attempts have), I would be very grateful! Thanks.
Update: I am attempting to do this with a modally presented vc now, and have attempted to use protocol callbacks but to no avail. Below is the code.
protocol MainVCDelegate: class {
func pushIt()
}
in the modally pushed view:
weak var delegate: MainVCDelegate?
#IBAction func changePartnerButton(_ sender: Any) {
delegate?.pushIt()
dismiss(animated: false)
}
in the main VC I implement the protocol and create the function to be run, but nothing happens.
In iOS 13 and iOS 14, you set yourself as the popover's presentation controller's delegate and implement presentationControllerDidDismiss. In iOS 12 and before, you set yourself as the popover's popover presentation controller's delegate and implement popoverPresentationControllerDidDismissPopover.

How does dismissing a presented UIViewController work?

Apple's View Controller Programming Guide for iOS states:
To dismiss a presented view controller, call the dismissViewControllerAnimated:completion: method of the presenting view controller. You can also call this method on the presented view controller itself. When you call the method on the presented view controller, UIKit automatically forwards the request to the presenting view controller.
This is verified by the UIViewController documentation:
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.
However this behavior seems ambiguous to me. What if a UIViewController is both presented and presenting? If you call dismiss(animated:completion:) on it, will it pass the call to its presentingViewController which will dismiss it, or will it dismiss its presentedViewController?
For example, suppose I have a UIViewController vc1, which creates and presents a UIViewController vc2, which then creates and presents vc3. So vc1 has vc2 as its presentedViewController, vc2 has vc1 as its presentingViewController and vc3 as its presentedViewController, and vc3 has vc2 as its presentedViewController. Then dismiss(animated:completion:) is called on vc2. Which is dismissed, vc2 or vc3? If vc2 is dismissed, what happens to vc3?

No animation when pushing view controllers in UINavigationController

I have a storyboard set up with a UITabBarController which contains a UINavigationController for each tab. For one of the UINavigationControllers there are no transition animations when pushing or presenting a view controller.
There are, at least, two different cases when this happens
1. I have a storyboard segue set up to push the child view controller. The segue triggers when selecting a cell in a table view. The "Animates"-box is checked.
Attempting to programatically push the child view controller yields the same result.
self.navigationController?.pushViewController(nextController, animated: true)
2. There is also no animation when attempting to modally present another view controller from the root view controller of the navigation controller.
modalViewController.modalTransitionStyle = UIModalTransitionStyle.flipHorizontal
self.present(modalViewController, animated: true, completion: nil)
If I present the modalViewController from another view controller the transition is animated which leads me to believe that there is something wrong in the root view controller that is presenting.
Is there a way to disable animations on a UIViewController that I might accidentally have triggered? I have checked and verified that there are no UIView.setAnimationsEnabled(false)
Use self.navigationController?.pushViewController( instead of self.present(
You set up animation in UINavigationController. But you called the function self.present( which is provided by UIViewController. UIViewController of course cannot provide the animation.
In my overridden viewWillDisappear(_ animated: Bool) of the parent view controller I had some code that reset the state of a custom view. The reset did in turn disable actions via CATransaction.setDisableActions(true), thus disabling the transition animations.
Moving the reset to viewDidDisappear(_ animated: Bool) resolved the issue.

Dismiss or remove previous modally presented view controller as soon as the next one appear modally

My target include a lot view need to present different view modally base on each user action. Here what I want to do to get cleaner view hierarchy and better user experience.
Root View Controller present First View Controller modally
When I clicked button on the First View Controller, then the Second View Controller appear modally over it.
As soon as the Second View Controller did appear, I want to dismiss or remove the first one from view hierarchy.
Can I do that? If so, how should i do it?
If not, what is the right way to solve this out cause I will present many modally presented view controllers over each view. I think even if I want to dismiss current view, the previous one will still remain appear when current one dismiss.
UPDATE :
VC1 (Root) > VC 2 (which was present modally) > VC 3 (which was
present modally over VC 2)
When i dismiss VC3, the VC2 is still on view memory. So, I don't want to appear VC2 as soon as I dismiss VC3 and instead I want to see VC1 by removing or dismissing VC2 from view hierarchy.
WANT : At the image, when I dismiss the blue,I don't want see the pink in my view memory and I want to remove it as soon as the blue one appear.
That's what i want to do.
Any Help?Thanks.
So, let's assume that you have a storyboard similar to:
What should happens is:
Presenting the the second ViewController (from the first ViewController).
Presenting the the third ViewController (from the second ViewController).
dismissing to the first ViewController (from the third ViewController).
In the third ViewController button's action:
#IBAction func tapped(_ sender: Any) {
presentingViewController?.presentingViewController?.dismiss(animated: true, completion: nil)
}
As you can see, by accessing the presentingViewController of the current ViewController, you can dismiss the previous hierarchy of the view controllers:
The view controller that presented this view controller.
By implementing presentingViewController?.presentingViewController? that means that: the presented of the presented current ViewController :)
It might seem a little bit confusing, but it is pretty simple.
So the output should be like (I added background colors to the viewControllers -as vc1: orange, vc2: black and vc3: light orange- to make it appears clearly):
EDIT:
If you are asking to remove the ViewController(s) in the middle (which in this example the second ViewController), dismiss(animated:completion:) does this automatically:
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.
Referring to what are you asking:
I think even if I want to dismiss current view, the previous one will
still remain appear when current one dismiss.
I think that appears clearly on the UI (and I find it ok), but as mentioned in the dismiss documentation discussion, both the third and the second will be removed from the stack. That's the right way.
Here is my opinion in different perspective,
Root View Controller present Second View Controller
Add FirstView onto Second View
Dismiss FirstView Controller when button pressed.
Second View Controller,
class ViewController: UIViewController, FirstViewControllerProtocol {
weak var firstViewController: FirstViewController?
override func viewDidLoad() {
super.viewDidLoad()
print("Not initiated: \(firstViewController)")
firstViewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "FirstViewController") as? FirstViewController
addChildViewController(firstVC!)
firstViewController?.delegate = self
view.addSubview((firstViewController?.view)!)
print("Initiated: \(firstViewController)")
}
func dismiss() {
firstViewController?.view.removeFromSuperview()
firstViewController?.removeFromParentViewController()
}
}
FirstViewController,
protocol FirstViewControllerProtocol {
// Use protocol/delegate to communicate within two view controllers
func dismiss()
}
class FirstViewController: UIViewController {
var delegate: FirstViewControllerProtocol?
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func dismiss(_ sender: Any) {
delegate?.dismiss()
}
deinit {
print("BYE")
}
}
What you want is an "unwind segue":
https://developer.apple.com/library/archive/featuredarticles/ViewControllerPGforiPhoneOS/UsingSegues.html#//apple_ref/doc/uid/TP40007457-CH15-SW8
https://developer.apple.com/library/archive/technotes/tn2298/_index.html
It allows you to dismiss multiple view controllers at the same time, without having to know how many there are in the stack.
In VC1 you would implement an IBAction called (for instance) unwindToRoot. Then in the storyboard for VC3, you wire up your Done button to the Exit object and choose the unwindToRoot action.
When that button is pressed, the system will dismiss all the view controllers it needs to bring you back to VC1.
This is better than calling presentingViewController?.presentingViewController?.dismiss(), because VC3 doesn't need to know anything about the view controller hierarchy underneath it.

How can I dismiss a UINavigationController presented modally?

I have the following structure:
UINavigationController(1) -> MainViewController ---PRESENT MODAL--->
UINavigationController(2) -> TutorialViewController ---PRESENT MODAL---> LoginViewController
---PRESENT MODAL---> SignupViewController
I want to dismiss the UINavigationController(2) from a user action on LoginViewController.
Any idea?
You should use delegation to dismiss the second view controller. So you would have the second nav controller be dismissed by the first nav controller, the one that presented it. This is the recommended way to dismiss modal views.
Here are the docs on delegation

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