Xamarin Forms: App is always restarting when resuming from background

Question

The datepicker UI is breaking and it is showing on top of the splash screen background like below:

Code:

<DatePicker

	x:Name="startdate_datepicker"

	Grid.Column="1"

	Format="MM/dd/yyyy"

	PropertyChanged="StartDateChoosed"

	HorizontalOptions="StartAndExpand"

	VerticalOptions="Center"/>

My Style:

<style name="MainTheme" parent="MainTheme.Base">

	<item name="android:forceDarkAllowed">false</item>

	<item name="android:windowBackground">@drawable/splashscreen</item>

	<item name="android:textAllCaps">false</item>

	<item name="colorPrimary">#e6e6e6</item>

	<item name="colorPrimaryDark">#000000</item>

	<item name="colorAccent">#808080</item>

I was using a single style for the entire app and that is the reason for this issue. For solving this issue I made some updates on Style and MainActivity.

Created a new style for splash:

<style name="MyTheme.Splash" parent="Theme.AppCompat.Light">

	<item name="android:forceDarkAllowed">false</item>

	<item name="android:windowBackground">@drawable/splashscreen</item>

	<item name="android:textAllCaps">false</item>

	<item name="colorPrimary">#e6e6e6</item>

	<item name="colorPrimaryDark">#000000</item>

	<item name="colorAccent">#808080</item>

</style>

<style name="MyTheme.Main" parent ="MainTheme.Base">

	<item name="windowActionBar">false</item>

	<item name="windowNoTitle">true</item>

	<item name="android:forceDarkAllowed">false</item>

	<item name="android:textAllCaps">false</item>

	<item name="colorPrimary">#e6e6e6</item>

	<item name="colorPrimaryDark">#000000</item>

	<item name="colorAccent">#808080</item>

</style>

MainActivity:

[Activity(

	Label = "App Name", 

	Theme = "@style/MyTheme.Main", 

	Icon = "@drawable/launcher_icon", 

	MainLauncher = false,

	NoHistory = true,

	Exported =true,

	ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation, 

	ScreenOrientation = ScreenOrientation.Portrait)]

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity

{

	protected override void OnCreate(Bundle savedInstanceState)

	{

		base.OnCreate(savedInstanceState, persistentState);

	}

}

[Activity(

		Theme = "@style/MyTheme.Splash",

		MainLauncher = true,

		NoHistory = true,

		ScreenOrientation = ScreenOrientation.Portrait)]

public class SplashActivity : AppCompatActivity

{

	public override void OnCreate(Bundle savedInstanceState, PersistableBundle persistentState)

	{

		base.OnCreate(savedInstanceState, persistentState);

	}

	protected override void OnResume()

	{

		base.OnResume();

		var startUp = new Task(() =>

		{

			var intent = new Intent(this, typeof(MainActivity));

			StartActivity(intent);

		});

		startUp.ContinueWith(t => Finish());

		startUp.Start();

	}

}

But now my app is always restarting when resuming from background due to the OnResume() code in SplashActivity. I need to stay on the same page if I resume from background. For that What change I need to do on SplashActivity?

Answer 1

Hello,

According to the community's security rules, demos in external links cannot be downloaded.

According to the code you provided, this issue is caused by recreating the MainActivity when calling the resume method when restoring the app from the background.

In fact, when creating SplashScreen, you can achieve this requirement with just one file from MainActivity.

Please refer to the following code sample.

[Activity(Label = "Mobile App",
        Theme = "@style/Your_Splash_Theme",
        Icon = "@drawable/Your_Icon",
        MainLauncher = true,
        ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation,
        LaunchMode = LaunchMode.SingleTop)]

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.Window.RequestFeature(WindowFeatures.ActionBar);
            // Name of the MainActivity theme you had there before.
            base.SetTheme(Resource.Style.MainTheme);
            base.OnCreate(savedInstanceState);

            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            LoadApplication(new App());
        }

      // other methods
}

Best Regards,

Alec Liu.

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