Develop Reference

How to enable/disable barcode scanner using Datawedge in Xamarin Forms

I am developing an inventory management app in xamarin forms using Zebra TC20 model. Right now I am able to retrieve barcode data using datawedge. Now I am trying to disable and enable barcode scanner using datawedge as well. I have surfed and found out we can broadcast to datawedge for enable and disable the barcode scanner. Now I am having the issue when I want to enable or disable the the scanner from a page I am retrieving an error message Java.Lang.NullPointerException: 'Attempt to invoke virtual method 'void android.content.Context.sendBroadcast(android.content.Intent)' on a null object reference . The scanner functions are implemented in Android file. I am using dependency service to call the scanner functions. I have attached the code I have done.
MainActivity.cs
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity, IKeyboardListener, IScannerConnection
{
private static string ACTION_DATAWEDGE_FROM_6_2 = "com.symbol.datawedge.api.ACTION";
private static string EXTRA_CREATE_PROFILE = "com.symbol.datawedge.api.CREATE_PROFILE";
private static string EXTRA_SET_CONFIG = "com.symbol.datawedge.api.SET_CONFIG";
private static string EXTRA_PROFILE_NAME = "Barcode Scan";
private DataWedgeReceiver _broadcastReceiver = null;
protected override void OnCreate(Bundle bundle)
{
base.Window.RequestFeature(WindowFeatures.ActionBar);
// Name of the MainActivity theme you had there before.
// Or you can use global::Android.Resource.Style.ThemeHoloLight
base.SetTheme(Resource.Style.MainTheme);
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(bundle);
DependencyService.Register<ToastNotification>(); // Register your dependency
ToastNotification.Init(this);
var container = new SimpleContainer(); // Create a SimpleCOntainer
container.Register<IGeolocator, Geolocator>(); // Register the Geolocator
container.Register<IDevice>(t => AndroidDevice.CurrentDevice); // Register the Device
Resolver.ResetResolver(); // Reset the resolver
Resolver.SetResolver(container.GetResolver()); // Resolve it
FFImageLoading.Forms.Platform.CachedImageRenderer.Init(enableFastRenderer: true);
UserDialogs.Init(this);
Rg.Plugins.Popup.Popup.Init(this, bundle);
global::Xamarin.Forms.Forms.Init(this, bundle);
global::ZXing.Net.Mobile.Forms.Android.Platform.Init();
_broadcastReceiver = new DataWedgeReceiver();
App inventoryApp = new App(OnSaveSignature);
_broadcastReceiver.scanDataReceived += (s, scanData) =>
{
MessagingCenter.Send<App, string>(inventoryApp, "ScanBarcode", scanData);
};
CreateProfile();
//DependencyService.Register<ToastNotification>();
//ToastNotification.Init(this, new PlatformOptions() { SmallIconDrawable = Android.Resource.Drawable.IcDialogInfo });
LoadApplication(inventoryApp);
}
public override void OnBackPressed()
{
if (Rg.Plugins.Popup.Popup.SendBackPressed(base.OnBackPressed))
{
// Do something if there are some pages in the `PopupStack`
}
else
{
// Do something if there are not any pages in the `PopupStack`
}
}
public override bool OnOptionsItemSelected(IMenuItem item)
{
// check if the current item id
// is equals to the back button id
if (item.ItemId == 16908332 && !RFIDStockCountViewModel.IsPosted && RFIDStockCountViewModel.IsStockCounting)
{
return false;
/*
if (Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack.Count > 0)
{
//LIFO is the only game in town! - so send back the last page
int index = Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack.Count - 1;
var currPage = (CustomContentPage)Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack[index];
// check if the page has subscribed to
// the custom back button event
if (currPage?.CustomBackButtonAction != null)
{
// invoke the Custom back button action
currPage?.CustomBackButtonAction.Invoke();
// and disable the default back button action
return false;
}
}
// if its not subscribed then go ahead
// with the default back button action
return base.OnOptionsItemSelected(item);
*/
}
else
{
// since its not the back button
//click, pass the event to the base
return base.OnOptionsItemSelected(item);
}
}
private async Task<bool> OnSaveSignature(Stream bitmap, string filename)
{
var path = Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryPictures).AbsolutePath;
var file = Path.Combine(path, "signature.png");
using (var dest = File.OpenWrite(file))
{
await bitmap.CopyToAsync(dest);
}
return true;
}
//public override void OnBackPressed()
//{
// if (Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack.Count > 0)
// {
// //LIFO is the only game in town! - so send back the last page
// int index = Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack.Count - 1;
// var currentpage = (CustomContentPage)Xamarin.Forms.Application.Current.MainPage.Navigation.NavigationStack[index];
// // check if the page has subscribed to
// // the custom back button event
// if (currentpage?.CustomBackButtonAction != null)
// {
// currentpage?.CustomBackButtonAction.Invoke();
// }
// else
// {
// base.OnBackPressed();
// }
// }
//}
public override bool OnKeyDown(Keycode keyCode, KeyEvent e)
{
if (e.KeyCode.GetHashCode() == 139 || e.KeyCode.GetHashCode() == 280)
{
MessagingCenter.Send<IKeyboardListener, string>(this, "KeyboardListener", "TRUE");
}
return base.OnKeyDown(keyCode, e);
}
public override bool OnKeyUp(Keycode keyCode, KeyEvent e)
{
if (e.KeyCode.GetHashCode() == 139 || e.KeyCode.GetHashCode() == 280)
{
MessagingCenter.Send<IKeyboardListener, string>(this, "KeyboardListener", "FALSE");
}
return base.OnKeyDown(keyCode, e);
}
protected override void OnResume()
{
base.OnResume();
if (null != _broadcastReceiver)
{
// Register the broadcast receiver
IntentFilter filter = new IntentFilter(DataWedgeReceiver.IntentAction);
filter.AddCategory(DataWedgeReceiver.IntentCategory);
Android.App.Application.Context.RegisterReceiver(_broadcastReceiver, filter);
}
}
protected override void OnPause()
{
if (null != _broadcastReceiver)
{
// Unregister the broadcast receiver
Android.App.Application.Context.UnregisterReceiver(_broadcastReceiver);
}
base.OnStop();
}
private void CreateProfile()
{
String profileName = EXTRA_PROFILE_NAME;
SendDataWedgeIntentWithExtra(ACTION_DATAWEDGE_FROM_6_2, EXTRA_CREATE_PROFILE, profileName);
// Now configure that created profile to apply to our application
Bundle profileConfig = new Bundle();
profileConfig.PutString("PROFILE_NAME", EXTRA_PROFILE_NAME);
profileConfig.PutString("PROFILE_ENABLED", "true"); // Seems these are all strings
profileConfig.PutString("CONFIG_MODE", "CREATE_IF_NOT_EXIST");
Bundle barcodeConfig = new Bundle();
barcodeConfig.PutString("PLUGIN_NAME", "BARCODE");
//barcodeConfig.PutString("RESET_CONFIG", "true"); // This is the default but never hurts to specify
Bundle barcodeProps = new Bundle();
barcodeProps.PutString("scanner_input_enabled", "true"); // This is the default but never hurts to specify
barcodeProps.PutString("scanner_selection_by_identifier", "AUTO ");
barcodeProps.PutString("scanner_selection", "auto ");
barcodeProps.PutString("aim_mode", "off ");
barcodeProps.PutString("illumination_mode", "off ");
barcodeConfig.PutBundle("PARAM_LIST", barcodeProps);
profileConfig.PutBundle("PLUGIN_CONFIG", barcodeConfig);
Bundle appConfig = new Bundle();
appConfig.PutString("PACKAGE_NAME", this.PackageName); // Associate the profile with this app
appConfig.PutStringArray("ACTIVITY_LIST", new String[] { "*" });
profileConfig.PutParcelableArray("APP_LIST", new Bundle[] { appConfig });
SendDataWedgeIntentWithExtra(ACTION_DATAWEDGE_FROM_6_2, EXTRA_SET_CONFIG, profileConfig);
// You can only configure one plugin at a time, we have done the barcode input, now do the intent output
profileConfig.Remove("PLUGIN_CONFIG");
Bundle intentConfig = new Bundle();
intentConfig.PutString("PLUGIN_NAME", "INTENT");
intentConfig.PutString("RESET_CONFIG", "true");
Bundle intentProps = new Bundle();
intentProps.PutString("intent_output_enabled", "true");
intentProps.PutString("intent_action", DataWedgeReceiver.IntentAction);
intentProps.PutString("intent_delivery", "2");
intentConfig.PutBundle("PARAM_LIST", intentProps);
profileConfig.PutBundle("PLUGIN_CONFIG", intentConfig);
SendDataWedgeIntentWithExtra(ACTION_DATAWEDGE_FROM_6_2, EXTRA_SET_CONFIG, profileConfig);
}
private void SendDataWedgeIntentWithExtra(String action, String extraKey, Bundle extras)
{
Intent dwIntent = new Intent();
dwIntent.SetAction(action);
dwIntent.PutExtra(extraKey, extras);
SendBroadcast(dwIntent);
}
private void SendDataWedgeIntentWithExtra(String action, String extraKey, String extraValue)
{
Intent dwIntent = new Intent();
dwIntent.SetAction(action);
dwIntent.PutExtra(extraKey, extraValue);
SendBroadcast(dwIntent);
}
public void SendScannerEnable()
{
SendDataWedgeIntentWithExtra(ACTION_DATAWEDGE_FROM_6_2, EXTRA_SET_CONFIG, "ENABLE_PLUGIN");
}
public void SendScannerDisable()
{
SendDataWedgeIntentWithExtra(ACTION_DATAWEDGE_FROM_6_2, EXTRA_SET_CONFIG, "DISABLE_PLUGIN");
}
}
}
Snip from Page.cs
protected override void OnAppearing()
{
DependencyService.Get<IScannerConnection>().SendScannerEnable();
MessagingCenter.Subscribe<App, string>(this, "ScanBarcode", (sender, arg) =>
{
ScanBarcode(arg);
});
base.OnAppearing();
}
I have searched through internet but I didn't get any resource on how to fix it.
Thank you.

The url below helped me to fix my problem. I had to create a new scanner class which enables and disables datawedge profile by triggering events. https://developer.zebra.com/community/home/blog/2018/07/11/xamarinforms-freshmvvm-datawedge-take-2

Refresh Fragment From Activity After Updating Data on SQLite Xamarin Android

I got an issue with my Android program when updating user data on Fragment_profile. Fragment_Profile loads User profile data and contains an update button in which the button navigates to an activity called EditProfileActivity. Users can technically update the data but, after they save the updated data, the data still can't be updated. The old data still appear. I try to refresh the fragment by using OnResume() and add OnRestart on my EditProfileActivity.cs and OnPause both in fragment and activity but, still nothing. I am using Xamarin Android and develop it with C#. For more info, you can see what happened in the GIF
My issue
So far, I've tried to code, and here's my code.
Fragment_profile.cs
public class Fragment_Profile : Android.Support.V4.App.Fragment
{
public HomePageActivity m_currentActivity;
public TextView m_tv_loginname, m_tv_username, m_tv_fullname , m_tv_dob;
public Boolean isRefreshing = false;
public override void OnCreate(Bundle aSavedInstanceState)
{
base.OnCreate(aSavedInstanceState);
}
//public static Fragment_Profile NewInstance(Model.User aCurrentUser)
public static Fragment_Profile NewInstance()
{
var _frag4 = new Fragment_Profile { Arguments = new Bundle() };
return _frag4;
}
public override View OnCreateView(LayoutInflater aInflater, ViewGroup aContainer, Bundle aSavedInstanceState)
{
var _ignored = base.OnCreateView(aInflater, aContainer, aSavedInstanceState);
var view= aInflater.Inflate(Resource.Layout.FragmentProfile, null);
m_tv_loginname = view.FindViewById<TextView>(Resource.Id.tv_loginname);
m_tv_username = view.FindViewById<TextView>(Resource.Id.tv_userEmail);
m_tv_fullname = view.FindViewById<TextView>(Resource.Id.tv_fullname);
m_tv_dob = view.FindViewById<TextView>(Resource.Id.tv_dob);
Button _updateProfile = view.FindViewById<Button>(Resource.Id.btnUpdateProfile);
_updateProfile.Click += _updateProfile_Click;
m_currentActivity = (HomePageActivity)this.Activity;
if (m_currentActivity.CurrentUser != null)
{
//string = "Welcome, " + m_currentActivity.CurrentUser.UserName;
m_tv_loginname.Text = m_currentActivity.CurrentUser.LoginName;
m_tv_fullname.Text = m_currentActivity.CurrentUser.UserName;
m_tv_username.Text = m_currentActivity.CurrentUser.UserEmail;
m_tv_dob.Text = m_currentActivity.CurrentUser.DateOfBirth;
}
else
{
Toast.MakeText(Activity, "The data is not found!", ToastLength.Short).Show();
Intent i = new Intent(Context, typeof(MainActivity));
StartActivity(i);
this.Activity.Finish();
}
return view;
}
private void _updateProfile_Click(object sender, EventArgs e)
{
Intent i = new Intent(Context, typeof(EditProfileActivity));
i.PutExtra("loginname", m_currentActivity.CurrentUser.LoginName);
i.PutExtra("fullname", m_currentActivity.CurrentUser.UserName);
i.PutExtra("useremail", m_currentActivity.CurrentUser.UserEmail);
i.PutExtra("dob", m_currentActivity.CurrentUser.DateOfBirth);
StartActivity(i);
}
public override void OnResume()
{
base.OnResume();
if (isRefreshing)
{
Fragment fragment = new Fragment_Profile();
Android.Support.V4.App.FragmentManager fragmentMg = Activity.SupportFragmentManager;
FragmentTransaction fragmentTrans = fragmentMg.BeginTransaction();
fragmentTrans.Replace(Resource.Id.content_frame, fragment);
fragmentTrans.Detach(fragment);
fragmentTrans.Attach(fragment);
fragmentTrans.Commit();
//adapter.notifyDataSetChanged();
}
}
public override void OnPause()
{
base.OnPause();
isRefreshing = true;
}
}
When user click the _updateProfile button It will reference to next activity which is EditProfileActivity. Here's my EditProfileActivity.cs
public class EditProfileActivity : Activity, IOnDateSetListener
{
public EditText m_editFullName, m_editUsername, m_dob;
public TextView m_tvEmail;
public Button m_btnUpdate;
public Boolean isRefreshing = false;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.EditProfile);
m_editFullName = FindViewById<EditText>(Resource.Id.et_editfullName);
m_editUsername = FindViewById<EditText>(Resource.Id.et_editUserName);
m_tvEmail = FindViewById<TextView>(Resource.Id.tv_Email);
m_dob = FindViewById<EditText>(Resource.Id.et_editDob);
m_btnUpdate = FindViewById<Button>(Resource.Id.btn_updateprofile);
m_btnUpdate.Click += _btnUpdate_Click;
m_dob.Click += _dob_Click;
Bundle extras = Intent.Extras;
m_editFullName.Text = extras.GetString("loginname");
m_editUsername.Text = extras.GetString("fullname");
m_tvEmail.Text = extras.GetString("useremail");
m_dob.Text = extras.GetString("dob");
}
private void _btnUpdate_Click(object sender, EventArgs e)
{
try
{
Model.User _currentUser = Model.User.CheckEmailUser(m_tvEmail.Text);
_currentUser.UserName = m_editUsername.Text;
_currentUser.LoginName = m_editFullName.Text;
_currentUser.UserEmail = m_tvEmail.Text;
_currentUser.DateOfBirth = m_dob.Text;
var _updated = DBManager.Instance.Update(_currentUser);
if (_updated > 0)
{
Toast.MakeText(this, "Your account has been succesfully updated!", ToastLength.Long).Show();
Finish();
OnResume();
}
else
{
Toast.MakeText(this, "Failed to update!", ToastLength.Long).Show();
}
}
catch(Exception ex)
{
Toast.MakeText(this, ex.ToString(), ToastLength.Short).Show();
}
}
private void _dob_Click(object sender, EventArgs e)
{
var _dateTimeNow = DateTime.Now;
DatePickerDialog _datepicker = new DatePickerDialog(this, this
, _dateTimeNow.Year, _dateTimeNow.Month, _dateTimeNow.Day);
_datepicker.Show();
}
public void OnDateSet(DatePicker view, int year, int month, int dayOfMonth)
{
m_dob.Text = new DateTime(year, month + 1, dayOfMonth).ToShortDateString();
}
protected override void OnRestart()
{
base.OnRestart();
if (isRefreshing)
{
isRefreshing = false;
Finish();
}
}
protected override void OnPause()
{
base.OnPause();
if (!isRefreshing)
isRefreshing = true;
}
}
I also have read some articles that have the same problems as me but, It still confusing me and still same. I know it's a simple thing but, It took a few days for me because I am a newby and I still don't get the solution.
Do you guys have any ideas? Would you like to help me? If you don't mind please check my source code so, I know what I am missing. Thank in advance for your help!

In you Fragment, you can override the OnResume method. If you back to the fragment from Acitivty. you should query the new data from DB, then set the new value to the controls in Fragment.
public override void OnResume()
{
base.OnResume();
PHName.Text = photoDAO.GetFirstPhotos(Id).PhotoName;
}
Here is running GIF.
You can see this lifecycle about Fragment. Every time you display the Fragment,OnResume method will be executed. You get the newest data from DB, then set it to the Fragment page.
Here is my demo.
https://drive.google.com/file/d/11dROKS7TtqAaVYkG8w6ZKpqnQJRBD87E/view

Facebook login failed in XAMARIN webview

I am making webview of working website, but in the webview the facebook login doesn't work. I enter email, pass, and when i click sign in, it retries me to the login page.. I need someone who knows C#, and Xamarin.Android. Thanks!
WebView web_view;
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Main);
web_view = FindViewById<WebView>(Resource.Id.webview);
web_view.Settings.JavaScriptEnabled = true;
var cookieManager = CookieManager.Instance;
cookieManager.SetAcceptCookie(true);
web_view.SetWebViewClient(new HelloWebViewClient());
web_view.LoadUrl("[MY LINK]");
}
public override bool OnKeyDown(Keycode keyCode, Android.Views.KeyEvent e)
{
if (keyCode == Keycode.Back && web_view.CanGoBack())
{
web_view.GoBack();
return true;
}
return base.OnKeyDown(keyCode, e);
}
public class HelloWebViewClient : WebViewClient
{
public override bool ShouldOverrideUrlLoading(WebView view, string url)
{
Uri uri = new Uri(url);
var cookieManager = CookieManager.Instance;
var cookieContainer = new CookieContainer();
cookieContainer.GetCookies(uri);
cookieManager.SetAcceptCookie(true);
cookieManager.RemoveAllCookie();
view.Settings.JavaScriptEnabled = true;
Console.WriteLine("{0}", url);
return false;
}
}
}

MvvmCross with Xamarin.Forms: Setup not called

I am trying to put together my existing Xamarin.Forms application with MvvmCross.Forms. Unfortunately I am not able to go through the initialization.
MainActivity.cs
[Activity(MainLauncher = true, Label = "Main Activity")]
public class MainActivity : FormsApplicationActivity
{
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
Forms.Init(this, bundle);
var app = new MvxFormsApp();
LoadApplication(app);
var presenter = (MvxFormsDroidPagePresenter) Mvx.Resolve<IMvxViewPresenter>(); // Exception
presenter.MvxFormsApp = app;
Mvx.Resolve<IMvxAppStart>().Start();
}
}
Setup.cs
public class Setup : MvxAndroidSetup
{
public Setup(Context applicationContext) : base(applicationContext)
{
}
protected override IMvxApplication CreateApp()
{
return new App();
}
protected override IMvxAndroidViewPresenter CreateViewPresenter()
{
var presenter = new MvxFormsDroidPagePresenter();
Mvx.RegisterSingleton<IMvxViewPresenter>(presenter);
return presenter;
}
}
I guess the problem is that the Setup is not called at all, not even the constructor. Am I right? What is wrong with the code?

The bootstrapping is done in the splash screen.
You have to remove MainLauncher = true from your MainActivity and add a splash screen like:
[Activity(MainLauncher = true
, Theme = "#style/Theme.Splash"
, NoHistory = true
, ScreenOrientation = ScreenOrientation.Portrait)]
public class SplashScreen
: MvxSplashScreenActivity
{
public SplashScreen()
: base(Resource.Layout.SplashScreen)
{
}
private bool _isInitializationComplete;
public override void InitializationComplete()
{
if (!_isInitializationComplete)
{
_isInitializationComplete = true;
StartActivity(typeof(MainActivity));
}
}
protected override void OnCreate(Android.OS.Bundle bundle)
{
Forms.Init(this, bundle);
Forms.ViewInitialized += (object sender, ViewInitializedEventArgs e) =>
{
if (!string.IsNullOrWhiteSpace(e.View.StyleId))
{
e.NativeView.ContentDescription = e.View.StyleId;
}
};
base.OnCreate(bundle);
}
}
If you need a working example, see our example app:
https://github.com/xabre/xamarin-bluetooth-le/tree/master/Source/BLE.Client

OnCreateView Called twice

I'm trying to create an activity with two tabs, one holding FragmentA and one holding FragmentB. Here is how I add the fragments to the Activity:
[Activity(Label = "My App")]
public class MyActivity : Activity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.ConnectionMenu);
ActionBar.NavigationMode = ActionBarNavigationMode.Tabs;
AddTab("A", new FragmentA());
AddTab("B", new FragmentB());
}
private void AddTab(string tabText, Fragment fragment)
{
var tab = ActionBar.NewTab();
tab.SetText(tabText);
tab.TabSelected += (sender, e) =>
{
e.FragmentTransaction.Replace(
Resource.Id.fragmentContainer,
fragment);
};
ActionBar.AddTab(tab);
}
}
When I rotate the orientation I want to keep fields filled out in the fragments the same. I save my data in OnSaveInstanceState and restore the data in OnActivityCreated. However, I'm noticing that the OnCreateView and OnActivityCreated methods are being called twice per rotate. The first time containing my filled in Bundle and the second time with bundle being null.
I assume that my error is in the MyActivity class but if you need more information let me know!

Given you create the fragment in your Activity.OnCreate(), you will always have 2 calls due to creating new ones in the method, and maintaining the old ones in the base.OnCreate(). What you should probably do is instead of always creating these fragments, you can search via a tag or ID for an existing fragment and use those in the Tabs instead.
i.e.
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.ConnectionMenu);
ActionBar.NavigationMode = ActionBarNavigationMode.Tabs;
if(savedInstanceState == null)
{
AddTab("A", new FragmentA());
AddTab("B", new FragmentB());
}
else
{
Fragment a = (FragmentA)SupportFragmentManager.FindFragmentByTag("my_tag_a");
Fragment b = (FragmentB)SupportFragmentManager.FindFragmentByTag("my_tag_b");
AddTab("A", a);
AddTab("B", b);
}
}

I ended up solving the issue. as #JonDouglas said you need to make sure the tab wasn't already loaded before creating a new fragment. To do this the fragment can be loaded from the FragmentManager class using a tag. During the TabSelected event if the fragment was not previously create, a new fragment is created and added to the event FragmentTransaction using the tag. During the TabUnselected event, if the fragment was created then it is detached.
I also added in a Bundle value to hold onto the last active tab.
Here is the code I used to solve the issue.
[Activity(Label = "My App")]
public class MyActivity : Activity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.ConnectionMenu);
ActionBar.NavigationMode = ActionBarNavigationMode.Tabs;
AddTab("A", "a_fragment", () => new FragmentA());
AddTab("B", "b_fragment", () => new FragmentB());
if (savedInstanceState != null)
{
var selectedTab = savedInstanceState.GetInt(
"ActionBar.SelectedNavigationIndex", 0);
ActionBar.SetSelectedNavigationItem(selectedTab);
}
}
protected override void OnSaveInstanceState(Bundle savedInstanceState)
{
base.OnSaveInstanceState(savedInstanceState);
savedInstanceState.PutInt(
"ActionBar.SelectedNavigationIndex",
ActionBar.SelectedNavigationIndex);
}
private void AddTab<TFragment>(
string tabText,
string tag,
Func<TFragment> ctor) where TFragment : Fragment
{
var tab = ActionBar.NewTab();
tab.SetText(tabText);
tab.SetTag(tag);
var fragment = FragmentManager.FindFragmentByTag<TFragment>(tag);
tab.TabSelected += (sender, e) =>
{
if (fragment == null)
{
fragment = ctor.Invoke();
e.FragmentTransaction.Add(
Resource.Id.fragmentContainer,
fragment,
tag);
}
else
{
e.FragmentTransaction.Attach(fragment);
}
};
tab.TabUnselected += (sender, e) =>
{
if (fragment != null)
{
e.FragmentTransaction.Detach(fragment);
}
};
ActionBar.AddTab(tab);
}
}