Attempt to present on whose view is not in the window hierarchy

Question

I am working on a project using ResearchKit, so I send the user into the task I create:

let taskViewController = ORKTaskViewController(task: SurveyTask, taskRunUUID: nil)
taskViewController.delegate = self
presentViewController(taskViewController, animated: true, completion: nil)

When the user is finished with the survey, he goes into:

func taskViewController(taskViewController: ORKTaskViewController, didFinishWithReason reason: ORKTaskViewControllerFinishReason, error: NSError?) {
    switch reason {
        case .Completed:

... }

Here I encounter a problem when I try to show an alert before

taskViewController.dismissViewControllerAnimated(true, completion: nil)

I get the below error:

Attempt to present UIAlertController: ... on ViewController: ... whose view is not in the window hierarchy

Any idea of how I could present the alert before dismissing the ViewController?

I use the below for the alert:

let alertView = UIAlertController(title: "Houps", message: "Could not connect to the server.", preferredStyle: .Alert)
alertView.addAction(UIAlertAction(title: "Ok", style: .Default, handler: nil))
presentViewController(alertView, animated: true, completion: nil)

EDIT: The code is as below:

if let httpResponse = response as? NSHTTPURLResponse {
                print("HTTP response: \(httpResponse.statusCode)")
                if httpResponse.statusCode == 201 {
                    taskViewController.dismissViewControllerAnimated(true, completion: nil)
                }
            } else {
                print("No HTTP response")
                let alertView = UIAlertController(title: "Houps", message: "Could not connect to the server.", preferredStyle: .Alert)
                alertView.addAction(UIAlertAction(title: "Ok", style: .Default, handler: nil))
                presentViewController(alertView, animated: true, completion: nil)

            }

Could you dismiss the view controller on the click of the "OK" button in your alert controller? — j.f., Mar 28 '16 at 15:15
I do not want to dismiss yet, I first want to show on alert. The dismissing is working just fine. The problem is showing the alert. — asheyla, Mar 28 '16 at 15:16
Yes, and @j.f. is saying to dismiss when tapping "OK" on the alert. — tktsubota, Mar 28 '16 at 15:16
Right, you show the alert, and then when the user clicks the "OK" button on the alert, dismiss the view controller. — j.f., Mar 28 '16 at 15:17
I can't show the alert. Sorry for not explaining better. I get problems showing the alert. — asheyla, Mar 28 '16 at 15:17
Yep, your problem is because you are trying to present the alert controller on a view controller that has now been dismissed, hence the "not in the window hierarchy" error. — j.f., Mar 28 '16 at 15:19
I have put an edit on the question to show how the code for the alert looks like and maybe for better explaining why I need to show the alert without dismissing. — asheyla, Mar 28 '16 at 15:24
Is there additional, relevant code that we can't see? From the snippet you provided, it looks like either the view controller is dismissed, _or_ you present the alert controller - which should work. — j.f., Mar 28 '16 at 15:35
The presenting of the alert does not work. It gives the error in the title: Attempt to present on whose view is not in the window hierarchy — asheyla, Mar 28 '16 at 15:38

score 1 · Answer 1 · answered Mar 28 '16 at 16:57

1

What object contains the httpResponse definition? The presentViewController() call looks like it's implicitly capturing self, on a view controller instance whose view perhaps is no longer in the view hierarchy when the response arrives.

answered Mar 28 '16 at 16:57

jwe

436
2
4

score 0 · Answer 2 · answered Mar 28 '16 at 16:05

0

You can try this

UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(yourAlertController, animated: true, completion: nil)

for presenting the UIAlertController.

answered Mar 28 '16 at 16:05

Waris Shams

1,606
1
15
27

score 0 · Accepted Answer · answered Mar 28 '16 at 21:29

0

You should call presentViewController on the taskViewController:ORKTaskViewController object

taskViewController.presentViewController(alertView, animated: true, completion: nil)

answered Mar 28 '16 at 21:29

Stefan

16
1

Attempt to present on whose view is not in the window hierarchy

3 Answers3