iOS Swift3 check if a ViewController has been initialized

Question

Is there a way to check if a ViewController has been initialized in iOS? I have an unwind Segue which does not work i a certain ViewController has not been initialized before.

if using navigation try this http://stackoverflow.com/a/42523549/5461400 — Harshal Valanda, Mar 03 '17 at 10:07
What do you mean by "has been initialized"? Please post the code that's causing you problems. You'll get more and better answers If you show what you've tried. See [Ask] — Ashley Mills, Mar 03 '17 at 10:28
Please post code and let us know your issue ("does not work"). — shallowThought, Mar 03 '17 at 10:56
I perform a Segue, which is an unwind segue. If the destination was never called at runtime, it can not unwind segue to the destination. For example, i have a StartVC, which decides if the user is already logged in, thus sending the user to the contentVC, or send him to the loginVC. Now if i logout in an app session where the app never called the LoginVC, the app wont perform the unwind segue. That is why i need a way to catch this case and perform a manual segue. Thank you guys for helping! — Jochen Österreicher, Mar 03 '17 at 11:05
The viewControllers are set up in the storyboard, so are the segues, they work if you open that loginVC in runtime, they do not work if loginVC is never accessed. I can not show you any code, i want you to show me code for how to check if my login was created! — Jochen Österreicher, Mar 03 '17 at 11:21

score 0 · Answer 1 · answered Mar 03 '17 at 10:13

0

You can check it using isKindOf class,

if view.isKind(of:UIViewcontroller.self) {
   //do your code while you know the view is initialised.
}

answered Mar 03 '17 at 10:13

Aashish

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score 0 · Answer 2 · answered Mar 03 '17 at 10:24

Find root view-controller then used it.

if self == UIApplication.shared.keyWindow?.rootViewController {
    /*do stuff*/
}

or u can used it also

if self.window.rootViewController is MyViewController {
//do something if it's an instance of that class
}

score 0 · Answer 3 · answered Mar 03 '17 at 10:30

0

UINavigationController manages the array(viewControllers) of all UIViewControllers which are invoked at that instance so do as below

For swift 3

let viewControllers: [UIViewController] = self.navigationController!.viewControllers
for aViewController in viewControllers {
if aViewController is YourViewController {

   // get vc here

    break
  }
}

For objective - c

for (UIViewController *controller in self.navigationController.viewControllers) {

        //Do not forget to import AnOldViewController.h
        if ([controller isKindOfClass:[YourViewController class]]) {

                   // get vc here
            break;
        }
    }

answered Mar 03 '17 at 10:30

dahiya_boy

9,298
1
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Thank you, but this only works if my view is insie a navigationController. The view i try to check for is a normal viewController. – Jochen Österreicher Mar 03 '17 at 11:19
@JochenÖsterreicher Please clear it either you wanted to check `UIView` or `UIViewController` – dahiya_boy Mar 03 '17 at 11:21
viewcontroller, sorry! – Jochen Österreicher Mar 03 '17 at 11:22
@JochenÖsterreicher If your required `UIViewController` is not in `NavController` that means that vc is not in memory so that `UIViewController` is not initialised at that instant. – dahiya_boy Mar 03 '17 at 11:29
VC is used for UIViewController. – dahiya_boy Mar 03 '17 at 11:29

iOS Swift3 check if a ViewController has been initialized

3 Answers3