This question is already asked here: https://forums.xamarin.com/discussion/32931/android-application-restarting, but no one has answered this yet.
I have a Xamarin.Forms application, and when the application starts, everything is okay, but sometimes, it restarts on its own after few minutes, this resets the current state of the app and goes to the main page.
My app has two activities: the first one is the MainLauncher and is the SplashScreen activity. The second activity is the one where my FormsApplication starts.
This is the second activity which restarts on its own on my Android 7.1.2 device in Debug mode (I didn't test in Release mode by the way).
The activity has the attribute LaunchMode.SingleTop attribute because I read in an other thread it would help, but with no luck.
I added breakpoints all over the activity to catch the process the activity is running through when the restart occurs, and it appears that the activity hits:
OnResume(), then
OnStop(), then
OnDestroy(), then
OnCreate(), then
OnStart()
But there is no reason for my activity to restart, and I hope somebody can help me or give me an hint because I am really stuck by this problem?
Thanks in advance.
Related
When I debug a Cordova app what I constantly do is step through its code inside Chrome's WebInspector. In order to be able to do this, however, I have to wait for the device to become ready in chrome://inspect/#devices (only then can I click on the appearing link for the started app). But if I do this the inspector will not halt on breakpoints if I am not quick enough. How do experienced Cordova developer tackle this issue?
Additionally to frank's comment I just found GapDebug which offers instant debug and, thus, comes close to what I deserve.
I have written file picker code in my project. When i run the project in my windows phone by clicking on device button in visual studio, the app runs fine(I mean it opens pictures library and i can select a photo and preview it).
But when I disconnect my usb and then open the app in the phone and when i open pictures library on click of a button , the pictures library opens briefly and then the app crashes immediately(My app closes).
Can anyone please help me with this??
As written in the blog post , the AndContinue method run in a different process and to do so, the current running app goes into the background or even gets closed sometimes, that is what you are experiencing in your app as far i can tell but not sure why different things happening during debug & deploy.
There must be a callback inside app.xaml.cs specifically to handle the condition when calling application(which was sent into background) comes in foreground, read this blog post carefully & you'll understand as what you need to change in your code :
using-the-andcontinue-methods-in-windows-phone
http://blogs.msdn.com/b/wsdevsol/archive/2014/05/08/using-the-andcontinue-methods-in-windows-phone-silverlight-8-1-apps.aspx
I just dealt with this issue and one of the reasons why there are differences between debug and deploy is because of the suspending event.
During debug, the application does not actually get suspended until you manually do it through Lifecycle Events. This means that when you pick a file on debug and the app is put to the background to load the file picker, it is not actually suspended, while when the app is deployed, it actually gets suspended.
Look into your app_resuming method and OnSuspending methods in your app.xaml that may be causing errors not occurring during debug.
I am trying to understand the application life cycle.
Scenario: I am launching a blank application; after that I am intentionally coming out of that app and opening a separate app. After some time I look at the Task Manager. The blank app appears to be suspended. Then I launch the blank app again (which was in a suspended state). At that moment, it has to hit the resuming event, right?
1) Why is the resuming event not firing? (Resuming event should be fired because the app is coming from the suspended state into the running state.)
2) Why is the OnLaunched event fired?
3) Is the OnLaunched event fired only when the application starts for first time, or also when being activated after termination?
Thanks in advance.
I don't have much experience with Metro apps yet, but I'll try to answer:
Ad 1) If your application went from the Suspended to Running state (as in diagram in this MSDN article on Metro Application Lifecycle), resuming event should actually fire. I made a few tests in similar scenario and it did. And btw, here's the best description of this event I found:
When an app is resumed from the Suspended state, it enters the Running state and continues from where it was when it was suspended. No application data is lost, as it was stored in memory. Therefore, most apps don't need to do anything when they are resumed. However, the app could have been suspended for hours or even days. So if your app has content or network connections that may have gone stale, these should be refreshed when the app resumes.
Ad 3) Launch for what I understand is just a special kind of Activation (one of the possible entry points to application), which corresponds to transition from Not running->Running. Some quotes:
When an app is activated, for any reason, the system sends the
Activated event.
and
When the user switches to your terminated app, the system sends the
Activated event, with Kind set to Launch and PreviousExecutionState
set to Terminated or ClosedByUser. The app should load its saved
application data and refresh its displayed content.
Ad 2) If OnLaunched was executed and Resuming event wasn't fired, my guess is your app was in 'Not Running state', e.g. it was terminated by the system (Suspended->Not Running) before you re-launched it. I don't know why task manager might have not refreshed this information.
I can answer this one:
1) but why the resuming event is not firing ? (resuming event needs to fired because the app is coming from suspended state to running state )
There is a debug button available for you to force your app into suspended state. In the quick-search of visual studio search for "debug location". This is a debug toolbar that you tap on the "suspend" button when you are debugging. Once you go back into your app (give it acouple seconds before you go back in) then you should get the resuming event fired.
ResumeEvent is not firing because you opened the app from the start screen or from its pinned tile. In that scenario, the app is treated as having been launched again. That's why the OnLaunched event was executed and not ResumeEvent.
To make sure ResumeEvent is fired, wait for 10 seconds after switching to other app, and then go to the top-left corner and bring the app back to the foreground. Make sure to wait the 10 seconds, before then Windows treats the app as running.
My wp7 app crashes when I come back from a task such as Map, Call or Web Browser. Infact, if i lock my phone and resume it again, still it crashes. Please tell me what could be the problem and how can I remove it?
There is a problem with you code.
Remove the application off the phone by starting a new emulator instance.
Open App.xaml.cs
Put a breakpoint in the method RootFrame_NavigationFailed and Application_UnhandledException
Now use the CallStack to find the root of the issue.
With no code posted (and in your case it could be ANYTHING in the project) you will be the best person to resolve your issue. If you can post a small reproduction on here we can take a look.
In application exit methods you probably should restore the data you dealt with last time before you quited
I have this issue when debugging mobile apps on the emulator. When I press F5, the build starts, then the deploy, then the app pops up in the emulator.
Because this takes a minute or 2, I am checking my SO score and maybe ask a question while I wait, and the emulator is in the background. When I finally switch back to the emulator, it shows the start page, not my app.
I figured out that by pressing the back button I can bring the debugged application to the foreground, but still, I don't know what is pushing it into the background to begin with. Has anybody noticed this, and found a way to prevent it?
The default behavior in WinMo is that if the device has no activity for a certain period of time (set in Settings->Today->Items->Today Timeout), the Today screen will come to the fore. Check to see if that's what's happening (though I think the smallest interval is still larger than a couple minutes).