I have this code in one of my IBAction (when a button is pressed), which is supposed to bring up a new view controller.
let addAlertVC = self.storyboard?.instantiateViewController(withIdentifier: "addAlert")
self.present(addAlertVC!, animated: false, completion: nil)
However, when I run the app and press the button that's supposed to take me to the new viewcontroller, but then I'm stuck with the original viewcontroller. I have put a print statement in the viewDidAppear function in the new view controller, and it is printing out whenever I press the button, so the new controller is definitely appearing. I have not dismissed the new controller anywhere in my app.
I have used the same code in other parts of my app, so I'm extremely confused as to why it's not working this time.
Any help would be greatly appreciated.
EDIT: I fixed my code. It turns out it wasn't how I was calling the view controller that was wrong, it was my button. Once I deleted and re-added the button, my code now works.
There is a good chance that your view controller is deallocated after you present it.
Try to declare your view controller outside of the function, in your controller. Something like:
class ViewController{
var addAlertVC:UIViewController?
...
func someFunction(){
addAlertVC = self.storyboard?.instantiateViewController(withIdentifier: "addAlert")
self.present(addAlertVC!, animated: false, completion: nil)
}
}
Related
I am a beginner, I am trying to add and edit data using a single view controller, process works fine, but when I try to click add button, view controller is pushed twice.
When I try to Open Click
But When I click Back in the navigation bar, the Screen appears with my designs.
Code For Launching Add Screen
let MenuAdd = self.storyboard?.instantiateViewController(identifier: "MenuEdit") as! AdminMenuVC
MenuAdd.IsEdit = true
self.navigationController?.pushViewController(MenuAdd, animated: true)
Code For Launching Edit Screen
let MenuEdit = self.storyboard?.instantiateViewController(identifier: "MenuEdit") as! AdminMenuVC
MenuEdit.IsEdit = true
self.navigationController?.pushViewController(MenuEdit, animated: true)
There are possible explanation for this:
You also have a storyboard segue going from the add button to the AdminMenuVC- if this is the case, just delete it (you are already pushing it from code)
You call from the first VC both self.navigationController?.pushViewController(MenuAdd, animated: true) and self.navigationController?.pushViewController(MenuEdit, animated: true) - they both refer to the same VC (AdminMenuVC). I cannot say if this is the case as you haven't posted the code. Be careful to check that you are not calling the two lines of code at the same time
Check button action you may be setting action and touch up inside actions on same button. You need to remove one action from reference inspector
What I want is to close a viewController after performing a segue so that the back button of the navigation controller on the new view doesn't go back to the view that I just closed, but it goes to the view that precedes it in the storyboard like it is the first time that it is loaded.
I already tried stuff like dismiss and so but it doesn't really work for me as it only closes the view in which the button that I pressed for performing the function is located :
#objc func goToList(){
self.dismiss(animated: true, completion: nil)
performSegue(withIdentifier: "goToList", sender: nil)
}
The navigation controller maintains a stack (array) of ViewControllers that have been opened (pushed). It also has the ability to pop these ViewControllers off the stack until it gets to a specific one.
For example, if you wished to return to a previous view controller of type MyInitialVC then you'd want to search through the stack until you found that type of VC, and then pop to it:
let targetVC = navigationController?.viewControllers.first(where: {$0 is MyInitialVC})
if let targetVC = targetVC {
navigationController?.popToViewController(targetVC, animated: true)
}
NB. written from memory without XCode, so you may need to correct minor typos
You can use unwind segue to get back to each viewController that you want.
Read more here:
Unwind Segues Step-by-Step (and 4 Reasons to Use Them)
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 would like to open the specific view from the notification widget.
normally other answers are create new view..(let viewcontroller = ... )
so If you continue to call, continue use memory..
So, I want to open viewA, which is already opened in my app, and then move to viewB.
My application structure is basically a viewA when the application is launched.
What I think is that instead of creating a new viewA, I want to move to viewB using the navigation.push from the already existing viewA.
The way to check whether a particular page already exists, how to show that page at the top , and how to navigation.push is work.
now i'm using this code to open viewA from Appdelegate
let MainView: Main_View_List_ = mainStoryboard.instantiateViewController(withIdentifier: "Main_List_View") as! Main_View_List_
let nav = UINavigationontroller.init(rootViewController: MainView)
UIApplication.topViewController()?.present(nav, animated: true, completion: nil)
Assuming you have access to the navigation controller, you'll want to do something like this to pop back to viewA:
for viewController in nav.viewControllers {
if viewController is ViewAClass {
viewController.pushViewBFlag = true
nav.popToViewController(viewController, animated: true)
return
}
}
Once you get back to viewA, you can check for pushViewBFlag and create and push viewB.
Alternately, since it seems that you are setting viewA as the root of your navigation controller, you could do: nav.popToRootViewControllerAnimated(true) to get back to viewA. You would need to then handle pushing viewB from viewA.
I bounce in a quite weird issue. When I push a specific view controller for another one, the former get dismissed soon after being showed. When I push it fom the main View Controller, it stays put without any problems. I put breakpoints and the viewDidDisappear is in fact called just after the viewDidAppear.
By smell it look like the second view controller becomes nil in one way, but how is it possible if that is wired to the storyboard?
Has anyone got any idea about what could be the reason for the weird behavior?
The main view controller and the first view controller are both in Swift, the pushed controller is still in Objective-c.
This is how I open the second view controller:
func didSelectRow(indexPath: NSIndexPath, from owner: DestinationsViewController){
if let currentElement=DestinationsContentProvider.sharedContentProvider().stations[indexPath.row]{
print("a \(indexPath.row) elemento \(currentElement)")
let targetModel = currentElement.model
//NSLog(#"targetMetro:%# targetPaletta=%#", owner.targetMetro, owner.targetPaletta);
if ((targetModel != nil) && (targetModel!.myTraffic != nil)){
targetModel!.segueExecute()
}
}
segueExecute is called on the model that is not dismissed. I put a breakpoint on the dealloc and it is never reached.
The only peculiar issue is that in the model I perform the segue on the main controller instead of the actual controller by this piece of code:
mapController.performSegueWithIdentifier("ShowWaiting", sender:self)
Still the same behavior happens even if I manually push the controller by executing:
let mainStoryboard:UIStoryboard!
if (UIDevice.currentDevice().userInterfaceIdiom == .Pad){
mainStoryboard=UIStoryboard(name:"StoryboardiPad", bundle: nil)
} else {
mainStoryboard=UIStoryboard(name:"MainStoryboard_iPhone", bundle: nil)
}
let controller = mainStoryboard.instantiateViewControllerWithIdentifier("Situation") as! StationSituation
controller.model=targetModel;
InArrivoHDViewController.sharedDetailController().navigationController?.pushViewController(controller, animated: true)
without using the segue construct.
Just check whether second view controller used for pushing is a property or not. If secondVC instance is created within the method in which pushing is done, secondVC will become nil after execution of the method.
I fixed the issue by directly calling performSegue on the view controller rather than delegating it to the root controller. For some reason this delegation works if there is the same kind of view controller on the Navigation queue in which you are pushing the controller: I have this construct in another class and I just checked it actually work. Otherwise the effect is the weird one I experienced.
I think, but I may not be sure, that in Objective-c the situation was different.