I'm using material design dialog for my iOS app written with swift. Here is the brief documentation of material design dialogs: https://material.io/develop/ios/components/dialogs/
I have a dialog which has 1 action and in the completion block of the action, I want to dismiss the view controller and go back to the previous view controller. The problem is that dismissing the view controller doesn't work. All instructions which are written in the completion block, such as printing something, execute except for dismissing view controller.
Here is my code :
DispatchQueue.main.async {
let alertStr = "Alert"
let alertController = MDCAlertController(title: "Error", message: alertStr)
let action = MDCAlertAction(title:"GoBack") { (action) in
self.dismiss(animated: false, completion: nil)
}
alertController.addAction(action)
self.present(alertController, animated:true, completion:nil)
}
I'd appreciate if you could help me figure out the problem.
Thanks in advance !
A couple of thoughts:
The dismiss(animated:completion:) “Dismisses the view controller that was presented modally by the view controller.” It’s not intended to dismiss the the view controller referenced by self.
Admittedly, dismiss will, “If you call this method on the presented view controller itself, UIKit asks the presenting view controller to handle the dismissal.” But you can’t rely upon that within the UIAlertAction for the button, because you don’t know when the dismissal of the MDCAlertController and when the action of the button is performed.
Are you sure you presented view controller and that it’s not, for example, having instead pushed on a navigation controller?
A good way of getting back to a prior view controller is an unwind segue (or see TN2298). That eliminates all ambiguity about “push” v “present” and whether dismiss will dismiss a presented view controller and instead pass the message to the presenting view controller.
have you tried to
performSegue(withIdentifier: "ViewControllerSegue", sender: nil)
you need to select your viewController on the top-bar the yellow square(name is what you predefine)
right-click and drag to the next view controller ---> Present Modally
then select the arrow and go to attributes inspector and name the identifier.
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.
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 have a storyboard set up with a tab bar controller and three tabs. Each tab has a navigation controller. The first tab has three scenes. There is a button (log out) in a view on the third tab that I would like to segue to the second scene on the first tab (corresponding to the log in view controller and connected to the first scene via Show(e.g., Push).
Here is what I've tried:
self.tabBarController?.selectedIndex = 0
This works, insofar as I get back to the first tab's initial scene after tapping the UIButton. But since I want to get to the second scene, this is not a complete solution. I think the solution may be along the lines of:
self.tabBarController?.selectedViewController = LoginViewController()
or
self.tabBarController?.setViewControllers(self.LoginViewController, animated: true)
But I do not want to create another instance of a view controller.
Can I still use .selectedIndex to implement a solution?
A simple solution u can try is
1. Set a Global variable (i.e in App Delegate) name as isLogoutClick of type boolean.
2. While you are on third tab and click on logout button then make the global variable "isLogoutClick" as true.
3.and then navigate to first tab (1st scene) and on viewDidLoad just check the condition that
if(appDelegate.isLogoutClick)
{
push your view to next scene.
}
4. make false the value of isLogoutClick.
5. make sure at initially the value of isLogoutClick is false.
try this might it will help you.
After setting selectedIndex to 0, perform the segue you want (in this example, "loginSegue"). You can name your segue in the storyboard if you haven't already.
tabBarController?.selectedIndex = 0
if let someViewController = tabBarController?.viewControllers?[0] as? SomeViewController {
someViewController.performSegueWithIdentifier("loginSegue", sender: nil)
}
I'm not sure if this works for tabBarController because I've used this for my navigationController but should work the same.
if let tab = self.tabBarController?.viewControllers {
if let index = find(tab.map { $0 is LoginViewController }, true) {
let destination = tab[index] as LoginViewController
tabBarController?.presentViewController(destination, animated: true, completion: nil)
}
}
With a navigationController I would use popToViewController but I'm not sure how the tabBarController exactly works
I want to use a push segue to edit an "entry" that is otherwise added via a present modally segue. It doesn't dismiss using the normal dismissViewControllerAnimated method when pressing cancel. Because of this I had to combine the popViewControllerAnimated method at the same time, so that depending on whether they click cancel when editing an entry or adding it, it will try both.
Both are done via NSNotifcation, because of objects I need to carry back from the last viewcontroller to the first:
func cancel(notification: NSNotification){
println("Cancel Executed")
let userInfo:Dictionary<String,EntryItem!> = notification.userInfo as Dictionary<String,EntryItem!>
entry = userInfo["Object"]
tableView.reloadData()
self.navigationController?.popViewControllerAnimated(true)
dismissViewControllerAnimated(true, completion: nil)
dataModel.saveEntries()
}
The problem with this is that if I go through the segues to arrive at the third view controller (in a string of 5), I cancel, and it goes back to the entries screen, but a messed up looking navigation bar takes the place of what is supposed to be there. There's no title showing either. It has a cancel button which causes a crash if you press it.
Here's what it's supposed to look like:
Here's what the popViewControllerAnimated does to it.