Access violation on resume in IOS

[billyb 1]

I am getting nowhere with an issue I thought might be a memory leak, but afer added code to get Low Memory warning event message it is not the case.

After using the Home button to suspend my app and run another IOS app and wait several minutes, if it return to my app and do anything I get a Access Viollation at address 00000001015C6BB0 accessing address 000000000000001A8.

The does not happen every time, but often.

 

I understand that this an error trying to reference a nill pointer, It happens when I try to click a button or show a dialog or edit a field on the form.

If I do the same suspend, but do not wait a few minutes, there is no error.

 

In one case I was able to pick a value from a dropdown list, but program locked up after selection of value,

 

My program has no timers running.

App uses SQLLite with TfdQuery and TFdmemtable

 

Do I need to do anything on IOS events

 AAppevent.aeWillBecomeInactive
 AAppevent.aeEnteredBackground

 

Any suggestions on how to proceed.

 

I am running IOS 10.4.6 ipad 7 gen delphi 10.4.2 sdk 13.6

 

 

Edited June 30, 2021 by billyb
add more details

[Guest]

13 minutes ago, billyb said:

Any suggestions on how to proceed.

First try to understand what is going on by getting clearer picture, find out what line in source code at this address 00000001015C6BB0,

Second if you can get the stack for this exception.

Third the problem is most likely something was freed and nilled then being used again, if this is the case then adding or capturing more events will not help here, because it your application with its code had freed something then assigned nil to it.

 

Hope that help.

[billyb 1]

I do not have option to find error address, this is Delphi FMX IOS app.

 

What is strange is that if I suspend to run another app and then resume (sometimes I get the access violation, othertimes I do not)

There does not appear to be any code that is run when my app is resumed by IOS. 

I am re-compiling in debug mode to see if I get more information when it access violates

 

 

[Rollo62 531]

I understand that your app starts and works, only when terminating it crashes after a while, is that correct ?

 

Are you doing some long operations in UI or threads, without properly stopping them before going to background ?

Did you ask for any unusual or dangerous permissions, which could cause such problems, or is it just a form-like DB application ?

 

[Dave Nottage 552]

On 7/1/2021 at 3:53 AM, billyb said:

I do not have option to find error address, this is Delphi FMX IOS app.

Is debugging from the IDE not working for you?