Crash on iOS 15 about btprogresshud

[marcoburato]

@Cheesebaron This is still not quite fixed, unfortunately. I've been adding some logging to my app to figure out why GetActiveWindow() would return null.

Here's the output from a crash report.

This is the normal condition immediately before calling BTProgressHUD.Show(), which works fine:

KeyWindow = <UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>
Windows =
  <UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>
    IsKeyWindow = True
    Hidden = False
    WindowLevel = 0
Scenes:
  <UIWindowScene: 0x104e12fb0; scene = <FBSScene: 0x281868600; identifier: sceneID:REDACTED>; persistentIdentifier = DEAEB509-D8BF-462C-9B07-15688ADF1DA8; activationState = UISceneActivationStateForegroundActive; settingsScene = <UIWindowScene: 0x104e12fb0>; windows = (
    "<UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>"
  )>
    Windows =
      <UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>
        IsKeyWindow = True
        Hidden = False
        WindowLevel = 0
ApplicationState = Active

This is the condition that causes the crash instead:

KeyWindow = 
Windows =
  <UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>
    IsKeyWindow = False
    Hidden = False
    WindowLevel = 0
Scenes:
  <UIWindowScene: 0x104d18db0; scene = <FBSScene: 0x281855380; identifier: sceneID:REDACTED>; persistentIdentifier = DEAEB509-D8BF-462C-9B07-15688ADF1DA8; activationState = UISceneActivationStateForegroundInactive; settingsScene = <UIWindowScene: 0x104d18db0>; windows = (
    "<UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>"
  )>
    Windows =
      <UIWindow: 0x10b510b10; frame = (0 0; 428 926); tintColor = UIExtendedSRGBColorSpace 0 0.588235 0.203922 1; gestureRecognizers = <NSArray: 0x283841380>; layer = <UIWindowLayer: 0x2838414d0>>
        IsKeyWindow = False
        Hidden = False
        WindowLevel = 0
ApplicationState = Inactive

Apparently, sometimes there is no KeyWindow and UIApplication.SharedApplication.ApplicationState == Inactive.

I'm not sure what the proper fix would be.
My app, like most others, only uses a single window. So, it's easy to just pick the only existing one.
In case of multiple windows, things are not so obvious. Perhaps in that use case it would make more sense to not use the convenience static methods and instead manually creating the ProgressHud with a new constructor that allows to specify the target window.

[Cheesebaron]

Can someone in this thread grab the artifact from this build and test my fix? https://github.com/redth-org/BTProgressHUD/pull/85/checks?check_run_id=3788006258

[mjo151]

We display a loading message at startup by calling BTProgressHUD.Show("Loading..."). The NRE occurs at that point and the stack trace indicates it is occurring on line 872 of ProgressHUD.cs. Looking at the code, I can see that UIApplication.SharedApplication.KeyWindow is still referenced.

Note that the problem doesn't happen every time the app is run, so it's not consistently reproducible.

[BramFP]

Adding to this for additional information, we've also experienced some crashes on iOS 15 but haven't tracked down the root cause yet.

Ours originates from Acr.UserDialogs which incorporates BTProgressHUD and we've got a different stack trace though, but just dropping it in here in case it might help.

ProgressHUD.PositionHUD (Foundation.NSNotification notification)
ProgressHUD.ShowProgressWorker (System.Single progress, System.String status, BigTed.ProgressHUD+MaskType maskType, System.Boolean textOnly, BigTed.ProgressHUD+ToastPosition toastPosition, System.String cancelCaption, System.Action cancelCallback, System.Double timeoutMs, System.Boolean showContinuousProgress, UIKit.UIImage displayContinuousImage)
ProgressHUD+<>c__DisplayClass18_0.<Show>b__0 ()
NSActionDispatcher.Apply ()
(wrapper managed-to-native) ObjCRuntime.Messaging.objc_msgSend(intptr,intptr,intptr,intptr,bool)
NSObject.InvokeOnMainThread (System.Action action)
ProgressHUD.Show (System.String status, System.Single progress, BigTed.ProgressHUD+MaskType maskType, System.Double timeoutMs)
BTProgressHUD.Show (System.String status, System.Single progress, BigTed.ProgressHUD+MaskType maskType)
ProgressDialog+<>c__DisplayClass17_0.<Refresh>b__0 ()
NSActionDispatcher.Apply ()
(wrapper managed-to-native) ObjCRuntime.Messaging.objc_msgSend(intptr,intptr,intptr,intptr,bool)
NSObject.InvokeOnMainThread (System.Action action)
ProgressDialog.Refresh ()
ProgressDialog.Show ()
AbstractUserDialogs.Progress (Acr.UserDialogs.ProgressDialogConfig config)
AbstractUserDialogs.Loading (System.String title, System.Action onCancel, System.String cancelText, System.Boolean show, System.Nullable`1[T] maskType)
AbstractUserDialogs.ShowLoading (System.String title, System.Nullable`1[T] maskType)

[mjo151]

I am also seeing a crash on iOS 15 when building against Xcode 13. I believe the problem is the use of UIApplication.SharedApplication.KeyWindow in the BTProgressHUB library. This property is deprecated and appears to be null in some cases, even after calling Window.MakeKeyAndVisible.

[Cheesebaron]

Hmm, interesting. I think we have to use UIApplication.SharedApplication.ConnectedScenes to get the foreground and active scene.

[nicobarengo]

Downloaded and installed... it's very unpredictable the crash, so I will get back with the results 🤞🏻

If someone need the NuGet for Acr.UserDialogs using the updated BTProgressHud (1.3.4) I made one for testing purposes
Acr.UserDialogs NuGet

[nicobarengo]

@Cheesebaron I can confirm that the issue is resolved with the the latest build.

[Cheesebaron]

OK, that is cool. Thanks for testing.

[Cheesebaron]

1.3.4 has been released on NuGet

[mjo151]

This doesn't appear to be completely resolved. Line 872 of ProgressHUD.cs is still accessing UIApplication.SharedApplication.KeyWindow. This resulted in an NRE when running my app.

[Cheesebaron]

@mjo151 can you please describe the scenario this happens in, so I can better test this?

[mjo151]

@Cheesebaron please let me know if you need any additional information to track down this issue.

[marcoburato]

@Cheesebaron Can you reopen this issue based on my last comment? Or should I create a new one?

[RobbiewOnline]

Hi, I'm also experiencing this crash on iOS 15 intermittently. I'm using BTProgressHud 1.3.5 and the Xamarin crash is...

MyProject 2022-05-04T22:10:59Z  UI  1 - IosPlatformDifferences - Display Message 'The pin does not match'

2022-05-04 23:11:06.324 MyProject.iOS[16396:1424514] [AppCenterCrashes] ERROR: +[MSACWrapperLogger MSACWrapperLog:tag:level:]/10 Unhandled Exception:
System.NullReferenceException: Object reference not set to an instance of an object
  at BigTed.ProgressHUD.PositionHUD (Foundation.NSNotification notification) [0x000cf] in /_/BTProgressHUD/ProgressHUD.cs:872 
  at Foundation.InternalNSNotificationHandler.Post (Foundation.NSNotification s) [0x00000] in /Users/builder/azdo/_work/2/s/xamarin-macios/src/Foundation/NSNotificationCenter.cs:48 
  at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x00013] in /Users/builder/azdo/_work/2/s/xamarin-macios/src/UIKit/UIApplication.cs:75 
  at MyProject.iOS.Application.Main (System.String[] args) [0x00001] in /Users/rob/GitHub/hillingar-MyProject-appv2/app/MyProject/MyProject.iOS/Main.cs:16 

2022-05-04 23:11:06.341 MyProject.iOS[16396:1424514] Unhandled managed exception: Object reference not set to an instance of an object (System.NullReferenceException)
  at BigTed.ProgressHUD.PositionHUD (Foundation.NSNotification notification) [0x000cf] in /_/BTProgressHUD/ProgressHUD.cs:872 
  at Foundation.InternalNSNotificationHandler.Post (Foundation.NSNotification s) [0x00000] in /Users/builder/azdo/_work/2/s/xamarin-macios/src/Foundation/NSNotificationCenter.cs:48 
  at (wrapper managed-to-native) UIKit.UIApplication.UIApplicationMain(int,string[],intptr,intptr)
  at UIKit.UIApplication.Main (System.String[] args, System.String principalClassName, System.String delegateClassName) [0x00013] in /Users/builder/azdo/_work/2/s/xamarin-macios/src/UIKit/UIApplication.cs:75 
  at MyProject.iOS.Application.Main (System.String[] args) [0x00001] in /Users/rob/GitHub/hillingar-MyProject-appv2/app/MyProject/MyProject.iOS/Main.cs:16 

[brunck]

@devology-rob you should open a new issue for this since this one is closed.

[RobbiewOnline]

@devology-rob you should open a new issue for this since this one is closed.

Thanks, I noticed afterwards and created #95 and it already looks like you may have fixed it 👏