I'm new with IOS and Swift so don't judge if solution is easy.
I have three ViewControllers like A,B and C.
I started from A -> NavigationController -> B -> NavigationController -> C
In specific situation I need to come back from C to A without seeing B. Is any way to do this?
Maybe changing the parent navigationController? Maybe I can print stack with every current view? - it will be really helpful.
I tried dismiss C and B view one by one and it work's but then we can see B view for a moment - so it's not a solution for me.
P.s : I'm using Modal kind to switch between controllers.
enter image description here
If A is always the first view controller, you can just do :
viewcontrollerC.navigationController?.popToRootViewController(animated: true)
This methods pop the stack to the first view controller, without displaying intermediates ones
If A is not the first viewController, you can do :
viewcontrollerC.navigationController?. popToViewController(viewControllerA, animated: true)
If you don't have a reference to viewControllerA, search it in the stack :
let viewControllerA: UIViewController?
for (let vc in (self.navigationController?.viewControllers ?? [])) {
//adust the test to find the appropriate controller
if vc.isKindOf(ViewControllerAClass.self) {
viewControllerA = vc
break
}
}
if let viewControllerA = viewControllerA {
self.navigationController?.popToViewController(viewControllerA, animated: true)
}
source : https://developer.apple.com/documentation/uikit/uinavigationcontroller/1621871-poptoviewcontroller
There are 2 ways you can achieve this. The simple to implement is in View Controller C you can, on in the specific situation, invoke following function:
navigationController?.popToRootViewController(animated: true)
This will pop all the navigational view hierarchy and take you back to the root i.e. the first view controller.
Second approach is to define unwind method in the view controller you want to go back to. In view controller when you start typing unwind, in Xcode 10 you will get autocomplete to add this Swift Unwind Segue Method.
#IBAction func unwindToA(_ unwindSegue: UIStoryboardSegue) {
let sourceViewController = unwindSegue.source
// Use data from the view controller which initiated the unwind segue
}
In this particular question let us say you added this method in View Controller A as you want to go back to it. I assume you have a button on View Controller C to go back to A. Controll+Drag from the button to the Exit symbol of the view controller A. The unwindToA method will automatically pop-up. Connect to it and you are done. When the user presses this button it will go back 2 navigation controllers to A.
Note: By this method you can go back to any navigation controller on the Navigation stack and it is not limited to root view controller alone. Below I am addition picture showing the exit on a view controller.
Related
Say I have view controllers A, B & C embedded in a navigation controller. From C, I present a new navigation controller for a separate logical flow but need to return back to A upon completion. So the app flow is as follows: A->B->C -- present new navigation controller modally -- D->E->F. Then go from F back to A.
I have set up an unwind segue, however, the unwind segue only takes me back to D even though I have set it up to return back to A.
How can I make it unwind all the way back to A? Am I missing something I don't see? Thank you.
Inside A:
#IBAction func unwindToHome(segue:UIStoryboardSegue){}
Then I have control-dragged from F to its 'exit' and chose the unwind segue I created in A, and wrote this segue code:
private let SEGUE_TO_HOME = "unwindToHome"
performSegue(withIdentifier: SEGUE_TO_HOME, sender: nil)
When you unwind, it should go back up the chain of view controllers, through all of those navigation controllers and modal presentations, to get all the way to the view controller that has this unwind action implemented.
Is it possible that unwindToHome occurs in any of these view controllers other than A? That's the only way I can see that the unwind action wouldn't sent you all the way back to A. I'm wondering if, for example, D has its own unwindToHome action (or perhaps is another instance of the same type as A). Bottom line, I cannot reproduce the behavior you describe except through something like that.
You subsequently asked:
I have put a deinit method in all of the above view controllers. I only print the word gone in all of them. when it unwinds back to A, 'gone' is only printed twice. Doesn't the unwind segue deallocate all instances?
Yes, they should all be deallocated. If not, the “debug memory graph” (see https://stackoverflow.com/a/30993476/1271826) is excellent at showing what is keeping a strong reference to the ones that are not deallocated. Most likely, these un-deallocated view controllers have some lingering strong reference cycle, repeating timer reference, or something like that which is keeping a strong reference to each, respectively.
You could simply create a reference to the first navigation controller that controllers A-C are embedded in by creating a subclass for the second nav controller.
class SecondNavController: UINavigationController {
// getter for previous nav controller
var prevNavController: UINavigationController? {
return parent?.navigationController
}
}
and when you need to unwind, simply:
class FController: UIViewController {
// other code
func unwindToRootController() {
guard let navController = navigationController as? SecondNavController,
let prevNavController = navController.prevNavController else {
return
}
navigationController.popToRootViewController(animated: true)
}
}
I want a my app can go to a first view controller when every time users want it.
So I want to create a function to dismiss all the view controllers, regardless of whether it is pushed in navigation controllers or presented modally or opened anything methods.
I tried various ways, but I failed to dismiss all the view controllers certainly.
Is there an easy way?
Try This :
self.view.window?.rootViewController?.dismiss(animated: true, completion: nil)
it should dismiss all view controllers above the root view controller.
If that doesn't work than you can manually do that by running a while loop like this.
func dismissViewControllers() {
guard let vc = self.presentingViewController else { return }
while (vc.presentingViewController != nil) {
vc.dismiss(animated: true, completion: nil)
}
}
It would dismiss all viewControllers until it has a presentingController.
Edit : if you want to dismiss/pop pushed ViewControllers you can use
self.navigationController?.popToRootViewController(animated: true)
Hope it helps.
If you are using Navigation you can use first one
or if you are presenting modally you can second one:
For Navigation
self.navigationController?.popToRootViewController(animated: true)
For Presenting modally
self.view.window!.rootViewController?.dismissViewControllerAnimated(false, completion: nil)
Hello everyone here is the answer for Swift-4.
To go back to root view controller, you can simply call a line of code and your work will be done.
self.view.window?.rootViewController?.dismiss(animated: true, completion: nil)
And if you have the splash screen and after that the login screen and you want to go to login screen you can simply append presentedviewcontroller in the above code.
self.view.window?.rootViewController?.presentedViewController!.dismiss(animated: true, completion: nil)
Simply ask your rootViewController to dismiss any ViewController if presenting.
if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
appDelegate.window?.rootViewController?.dismiss(animated: true, completion: nil)
(appDelegate.window?.rootViewController as? UINavigationController)?.popToRootViewController(animated: true)
}
The strategy to go back to your initial view controller could vary depending on your view controllers are stacked.
There could be multiple scenarios and depending on your situation, you can decide which approach is the best.
Scenario 1
Navigation controller is set as the root view controller
Navigation controller sets View Controller A as the root
Navigation controller pushes View Controller B
Navigation controller pushes View Controller C
This is a straightforward scenario where navigationController?.popToRootViewController(animated:true) is going to work from any view controller and return you back to View Controller A
Scenario 2
Navigation controller is set as the root view controller
Navigation controller sets View Controller A as the root
View Controller A presents View Controller B
View Controller B presents View Controller C
This scenario can be solved by the answers above
self?.view.window?.rootViewController.dismiss(animated: true) and will bring you back to View Controller A
Scenario 3
Navigation controller 1 is set as the root view controller
Navigation controller 1 sets View Controller A as the root
Navigation controller 1 pushes View Controller B
View Controller B presents Navigation Controller 2
Navigation Controller 2 sets View Controller D as the root
Navigation controller 2 pushes View Controller E
Now imagine that you need to go from View Controller E all the way back to A
Using the 2 answers above will not solve your problem this time as popping to root cannot happen if the navigation controller is not on the screen.
You might try to add timers and listeners for dismissing of view controllers and then popping which can work, I think there was an answer like this above with a function dismissPopAllViewViewControllers - I notice this leads to unusual behavior and with this warning Unbalanced calls to begin/end appearance transitions for
I believe what you can do to solve such scenarios is to
start by presenting your modal views controllers from the navigation controller itself
now you have better control to do what you want
So I would change the above to this architecture first:
Navigation controller 1 is set as the root view controller (same)
Navigation controller 1 sets View Controller A as the root (same)
Navigation controller 1 pushes View Controller B (same)
Navigation controller 1 presents Navigation Controller 2 (change)
Navigation Controller 2 sets View Controller D as the root (same)
Navigation controller 2 pushes View Controller E (same)
Now from View Controller E, if you add this:
let rootViewController = self?.view.window?.rootViewController as? UINavigationController
rootViewController?.setViewControllers([rootViewController!.viewControllers.first!],
animated: false)
rootViewController?.dismiss(animated: true, completion: nil)
you will be transported all the way back to View Controller A without any warnings
You can adjust this based on your requirements but this is the concept on how you can reset a complex view controller hierarchy.
Use this code for dismiss presented viewcontrollers and pop to navigation rootviewcontroller swift 4
// MARK:- Dismiss and Pop ViewControllers
func dismissPopAllViewViewControllers() {
if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
appDelegate.window?.rootViewController?.dismiss(animated: true, completion: nil)
(appDelegate.window?.rootViewController as? UINavigationController)?.popToRootViewController(animated: true)
}
}
Swift 5.4:
self.navigationController?.popToRootViewController(animated: true)
Pops all the view controllers on the stack except the root view controller and updates the display.
func popToRootViewController(animated: Bool)
But if you want to go to specific controller just use the below function.
func popToViewController(UIViewController, animated: Bool)
Pops view controllers until the specified view controller is at the top of the navigation stack.
To achieve what you want, modify your navigation stack, then do popViewController.
let allControllers = NSMutableArray(array: navigationController!.viewControllers)
let vcCount = allControllers.count
for _ in 0 ..< vcCount - 2 {
allControllers.removeObject(at: 1)
}
// now, allControllers[0] is root VC, allControllers[1] is presently displayed VC. write back to nav stack
navigationController!.setViewControllers(allControllers as [AnyObject] as! [UIViewController], animated: false)
// then pop root VC
navigationController!.popViewController(animated: true)
See this for the way to further manipulate the navigation stack. If your topmost VC is modal, dismiss it first before the code above.
Create an Unwind Segue (You can find it at https://developer.apple.com/library/archive/featuredarticles/ViewControllerPGforiPhoneOS/UsingSegues.html copyright of Apple Inc.)
Unwind segues let you dismiss view controllers that have been
presented. You create unwind segues in Interface Builder by linking a
button or other suitable object to the Exit object of the current view
controller. When the user taps the button or interacts with the
appropriate object, UIKit searches the view controller hierarchy for
an object capable of handling the unwind segue. It then dismisses the
current view controller and any intermediate view controllers to
reveal the target of the unwind segue.
To create an unwind segue
Choose the view controller that should appear onscreen at the end of an unwind segue.
Define an unwind action method on the view controller you chose.
The Swift syntax for this method is as follows:
#IBAction func myUnwindAction(unwindSegue: UIStoryboardSegue)
The Objective-C syntax for this method is as follows:
- (IBAction)myUnwindAction:(UIStoryboardSegue*)unwindSegue
3. Navigate to the view controller that initiates the unwind action.
Control-click the button (or other object) that should initiate the unwind segue. This element should be in the view controller you want to dismiss.
Drag to the Exit object at the top of the view controller scene.
https://developer.apple.com/library/archive/featuredarticles/ViewControllerPGforiPhoneOS/Art/segue_unwind_linking_2x.png
Select your unwind action method from the relationship panel.
You must define an unwind action method in one of your view controllers before trying to create the corresponding unwind segue in Interface Builder. The presence of that method is required and tells Interface Builder that there is a valid target for the unwind segue.
In case anyone looking for an Objective-C implementation of the question's answer,
[self.view.window.rootViewController dismissViewControllerAnimated:true completion:nil];
func dismiss_all(view: UIView){
view.window!.rootViewController?.dismiss(animated: true, completion: nil)
}
May be what you are looking for is unwind segue.
Unwind segues give you a way to "unwind" the navigation stack back
through push, modal, popover, and other types of segues. You use
unwind segues to "go back" one or more steps in your navigation
hierarchy.
Link to documentation:
https://developer.apple.com/library/archive/technotes/tn2298/_index.html
The best and prefered way to do this is to create an unwind segue. Just follow this documentation https://developer.apple.com/library/archive/featuredarticles/ViewControllerPGforiPhoneOS/UsingSegues.html. It can de done in code or through the interface builder.
I am currently implementing the XLPagerTabStrip (https://github.com/xmartlabs/XLPagerTabStrip) which effectively creates a tab bar at the top of the view controller. I want to be able to segue to a new view controller from one of the tabbed controllers and be able to use the navigation bar to move backwards (or a custom version of the navigation bar if this isn't possible).
XLPagerTabStrip provides the moveToViewController and moveToViewControllerAtIndex functions to navigate between child view controllers, but this method doesn't allow use of a navigation bar to go backwards.
Conceptually XLPagerTabStrip is a collection of view controllers declared and initialized during the XLPagerTabStrip model creation.
It has virtually no sense to use a UINavigationController if you already have all the viewcontrollers available.
You can create a global var previousIndex to store the previous viewController index and allow users to go back by using canonical methods:
func moveToViewControllerAtIndex(index: Int)
func moveToViewControllerAtIndex(index: Int, animated: Bool)
func moveToViewController(viewController: UIViewController)
func moveToViewController(viewController: UIViewController, animated: Bool)
About a new viewController, suppose you have 4 viewControllers that built your container (XLPagerTabStrip) named for example z1, z2, z3 e z4.
You can embed to z4 a UINavigationController (so it have the z4 controller as rootViewController) and start to push or pop your external views. When you want to return to your z4 you can do popToRootViewControllerAnimated to your UINavigationController
When you are go back to z4 , here you can handle your global var previousIndex to moving inside XLPagerTabStrip.
I'm not familiar with XLPagerTabStrip, but I had a similar problem recently and the solution was to use an unwind segue to go back to the previous view controller. It's pretty trivial to implement so probably worth a try.
To navigate back to your previous view tab controller, you had initially navigated from;
Embed your new view controller, from which you wish to navigate
away from in a navigation bar
Connect it's Navigation Bar Button to the Parent view containing the
tab bar by dragging a segue between the 2 views
Create a global variable in App delegate to store current index
which you will use in the Parent view to determine what tab view
controller to be shown
var previousIndex: Int = 0 //0 being a random tab index I have chosen
In your new view controller's (the one you wish to segue from)
viewdidload function, create an instance of your global variable as
shown below and assign a value to represent a representative index
of the child tab bar view controller which houses it.
//Global variable instance to set tab index on segue
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.previousIndex = 2
You can write this for as many child-tab connected views as you wish, remembering to set the appropriate child-tab index you wish to segue back to
Now, create a class property to reference your global variable and a function in your Parent view as shown below
let appDelegatefetch = UIApplication.shared.delegate as! AppDelegate
The function
func moveToViewControllerAtIndex(){
if (appDelegatefetch.previousIndex == 1){
self.moveToViewControllerAtIndex((self.appDelegatefetch.previousIndex), animated: false)
} else if (appDelegatefetch.previousIndex == 2){
self.moveToViewControllerAtIndex((self.appDelegatefetch.previousIndex), animated: false)
}
}
You may now call this function in the Parent View Controller's viewDidLoad, as shown below.
moveToViewControllerAtIndex()
Run your project and that's it.
Using the diagram below as a reference, I'm trying to go from controller A to controller B-2 when the users pushes a button.
I'm fairly new to iOS so I'm having some problems.
If I push the B-2 controller or create a segue the hierarchy is not respected and the B-2 controller is not inside the navigation controller (B).
I want the user to still have the navigation funcionalities and to still be able to go back to controller B-1 using the back button.
Controllers A & B are both under the same Tab controller (Z)
How can I achieve this?
In the end I found this solution:
From controller A I get the parent (Z), set the active controller to the second child (B) and get his child (B-1).
Once I have B-1 I can call perform segue and it works pretty good.
The hierarchy is correct and it's exactly the behaviour I wanted
The code is this
if let tab = self.parentViewController as? UITabBarController{
tab.selectedIndex = 1
if let one = tab.childViewControllers[1] as? UINavigationController{
if let two = one.childViewControllers[0] as? MatchTableViewController{
two.performSegueWithIdentifier("open_chat_view", sender: matchModel)
}
}
}
A user is in a view controller which calls a modal. When self.dismissViewController is called on the modal, a function needs to be run on the initial view controller. This function also requires a variable passed from the modal.
This modal can be displayed from a number of view controllers, so the function cannot be directly called in a viewDidDisappear on the modal view.
How can this be accomplished in swift?
How about delegate?
Or you can make a ViewController like this:
typealias Action = (x: AnyObject) -> () // replace AnyObject to what you need
class ViewController: UIViewController {
func modalAction() -> Action {
return { [unowned self] x in
// the x is what you want to passed by the modal viewcontroller
// now you got it
}
}
}
And in modal:
class ModalViewController: UIViewController {
var callbackAction: Action?
override func viewDidDisappear(_ animated: Bool) {
let x = … // the x is what you pass to ViewController
callbackAction?(x)
}
}
Of course, when you show ModalViewController need to set callbackAction like this modal.callbackAction = modalAction() in ViewController
The answer supplied and chosen by the question asker (Michael Voccola) didn't work for me, so I wanted to supply another answer option. His answer didn't work for me because viewDidAppear does not appear to run when I dismiss the modal view.
I have a table and a modal VC that appears and takes some table input. I had no trouble sending the initial VC the modal's new variable info. However, I was having trouble getting the table to automatically run a tableView.reloadData function upon dismissing the modal view.
The answer that worked for me was in the comments above:
You likely want to do this using an unwind segue on the modal, that
way you can set up a function on the parent that gets called when it
unwinds. stackoverflow.com/questions/12561735/… – porglezomp Dec 15
'14 at 3:41
And if you're only unwinding one step (VC2 to VC1), you only need a snippet of the given answer:
Step 1: Insert method in VC1 code
When you perform an unwind segue, you need to specify an action, which
is an action method of the view controller you want to unwind to:
#IBAction func unwindToThisViewController(segue: UIStoryboardSegue) {
//Insert function to be run upon dismiss of VC2
}
Step 2: In storyboard, in the presented VC2, drag from the button to the exit icon and select "unwindToThisViewController"
After the action method has been added, you can define the unwind
segue in the storyboard by control-dragging to the Exit icon.
And that's it. Those two steps worked for me. Now when my modal view is dismissed, my table updates. Just figured I'd add this, in case anyone else's issue wasn't solved by the chosen answer.
I was able to achieve the desired result by setting a Global Variable as a boolean value from the modal view controller. The variable is initiated and made available from a struct in a separate class.
When the modal is dismissed, the viewDidAppear method on the initial view controller responds accordingly to the value of the global variable and, if needed, flips the value on the global variable.
I am not sure if this is the most efficient way from a performance perspective, but it works perfectly in my scenario.