I implemented a Dependency Service to display alert box in my xamarin forms app.My app crashes when I call the alert box in android.
Here is My code
Android.App.AlertDialog.Builder _dialog = new AlertDialog.Builder(Android.App.Application.Context);
AlertDialog _alertDialog = _dialog.Create();
_alertDialog.SetTitle("Unauthorized");
_alertDialog.SetMessage("Please login again to continue using the App);
_alertDialog.SetButton("OK", (c, ev) => { CloseApp(); });
_alertDialog.Show();
It throws an exception:-Unable to add window -- token null is not for an application in android.
How to fix this Please help me
Unable to add window -- token null is not valid; is your activity running?
You are using a Application context and you need to use an Activity based one.
So you need the current Activity's context within your Forms' dependancy class which you can obtain that via multiple methods; A static var on the MainActivity, using the "CurrentActivityPlugin", etc...
As a quick fix, add a static Context variable to your MainActivity class and set it in the OnResume override.
public static Context context;
protected override void OnResume()
{
context = this;
base.OnResume();
}
Then change your context to that static one:
Android.App.AlertDialog.Builder _dialog = new Android.App.AlertDialog.Builder(MainActivity.context);
I'm trying to embed Forms XAML view into Xamarin Native application with MvvmCross 6.0.
I tried to reproduce effect of this solution but I got stuck on registering IMvxFormsViewPresenter. I also followed this tutorial.
I have simple MainContainerActivity with MainFragment (with corresponding MainViewModel in Core) that contains a button to Forms SettingsActivity/SettingsViewModel.
Full source can be found in the test repository.
Currently, I struggle with an exception thrown in base.OnCreate(bundle); while navigating to SettingsViewModel:
MvvmCross.Exceptions.MvxIoCResolveException has been thrown
Failed to resolve type MvvmCross.Forms.Presenters.IMvxFormsViewPresenter
I cannot find a way to register this Forms Presenter. I tried to do it in Setup but with no success.
I also tried to resolve MvxFormsAndroidViewPresenter in SplashActivity but Mvx.Resolve<IMvxViewPresenter>() as MvxFormsAndroidViewPresenter; yields null.
Do you have any idea what should I do to incorporate Forms views into MvvmCross 6.0 native application?
namespace MvvmCrossFormsEmbedding.Droid.Views
{
[Activity(Theme = "#style/AppTheme",
Label = "SettingsActivity")]
public class SettingsActivity : MvxFormsAppCompatActivity<SettingsViewModel>
{
public static SettingsActivity Instance { get; private set; }
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// #1 Initialize
Forms.Init(this, null);
SetContentView(Resource.Layout.activity_settings);
var toolbar = FindViewById<Toolbar>(Resource.Id.layout_toolbar);
SupportActionBar.Title = "Settings";
Instance = this;
// #2 Use it
var frag = new SettingsView().CreateFragment(this);
var ft = FragmentManager.BeginTransaction();
ft.Replace(Resource.Id.fragment_frame_layout, frag, "main");
ft.Commit();
}
}
}
Syncfusion sfchart working fine in android but generating error in IOS. here is my AppDelegate class code
AppDelegate:
namespace ProjectName
{
[Register ("AppDelegate")]
public class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
{
public override bool FinishedLaunching (UIApplication app, NSDictionary options)
{
new Syncfusion.SfChart.XForms.iOS.Renderers.SfChartRenderer();
global::Xamarin.Forms.Forms.Init ();
Appearance.Configure ();
LoadApplication (new App());
return base.FinishedLaunching (app, options);
}
}
}
If I remove 'new Syncfusion.SFChart.Xforms.IOS.Renderer.SfChartRenderer' from Code it run without generating any error or any result but when I put this line of code then it throw error which is
foundation.monotouchexception objective-c exception thrown
We were not able to reproduce the reported issue at our end and we have prepared a sample for this. Please check the attached sample.
Note: We suggest you to use Init method of SfChartRenderer as per the below code.
Code Example:
Syncfusion.SfChart.XForms.iOS.Renderers.SfChartRenderer.Init();
If you are still facing this issue, please update us the Xamarin Studio / Visual Studio version. Please download the sample from the following location.
Sample: http://www.syncfusion.com/downloads/support/forum/131907/ze/ChartGettingStarted1268455699
Regards,
Saravana Pandian M.
I have an application that I'm attempting to put Xamarin UI Tests on. I need to Backdoor the app to bypass my login process.
My Backdoor method fires just fine.
[Activity(Label = "AppName", Icon = "#drawable/icon", Theme = "#style/Theme.Splash", MainLauncher = true, NoHistory = true)]
public class SplashActivity : Activity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
StartActivity(typeof(MainActivity));
}
[Java.Interop.Export("BackDoor")]
public void BackDoor()
{
var myActivity = {Magic code to get reference to the the instance of MainActivity goes here}
}
}
However its firing in my Splash screen and I need it get a reference to my actual MainActivity not my SplashActivity. How do I get a reference to the MainActivity in my BackDoor method?
Xamarin Backdoor Docs:
https://developer.xamarin.com/recipes/testcloud/start-activity-with-backdoor/
https://developer.xamarin.com/guides/testcloud/uitest/working-with/backdoors/
According to the guide for a backdoor method for Android, it can not return object type, only string, Java.Lang.String, or void. See: https://developer.xamarin.com/guides/testcloud/uitest/working-with/backdoors/
Don't you want to start the next Activity from the backdoor as in the guide? If so, just follow the guide you linked more closely.
Also, just double checked and returning object from the BackDoor method fails on build with a NullReferenceException. However, for "{Magic code to get reference to the the instance of MainActivity goes here}" you can do:
ActivityManager am = (ActivityManager)this.GetSystemService(Context.ActivityService);
var myActivity = am.GetRunningTasks(1)[0].TopActivity;
the myActivity will be a reference to the top most activity, but you can't return it from the BackDoor method anyway. You can return a string description of course. I do not know why you need a reference to the activity in your test code anyway as there is not much you can do with it in the test code.
How To Retrieve Current Activity
To retrieve the MainActivity, you can use #JamesMontemagno's CurrentActivityPlugin.
Add the Current Activity NuGet Package into your Xamarin.Android project, and then, in your Xamarin.Android Project, you can use the following line of code to retrieve the current activity and check that it is the MainActivity.
Activity currentActivity = Plugin.CurrentActivity.CrossCurrentActivity.Current.Activity as MainActivity;
if (!(currentActivity is MainActivity))
throw new System.Exception("Current Activity is not MainActivity");
This plugin is open-sourced on GitHub.
I want to make a Xamarin.Forms project, targeting iOS, Android and Windows Phone.
My app needs to authenticate users using Facebook.
Should I implement login for each platform independently, or use a manual flow?
https://developers.facebook.com/docs/facebook-login/manually-build-a-login-flow/v2.0
I prefer to have a single implementation of the login flow, and use it on all platforms.
How can I get a single implementaion of the Facebook login flow?
UPDATE (10/24/17): While this way of doing things was okay a few years ago, I now strongly advocate for using native UI for doing authentication, as opposed to the webview method shown here. Auth0 is a great way to accomplish native UI login for your apps, using a wide variety of identity providers:
https://auth0.com/docs/quickstart/native/xamarin
EDIT: I finally put a sample for this on Gihub
I posted an answer on the Xamarin Forums. I'll repeat it here.
Let's start with the core of the app, the Xamarin.Forms PCL project. Your App class will look something like this:
namespace OAuth2Demo.XForms
{
public class App
{
static NavigationPage _NavPage;
public static Page GetMainPage ()
{
var profilePage = new ProfilePage();
_NavPage = new NavigationPage(profilePage);
return _NavPage;
}
public static bool IsLoggedIn {
get { return !string.IsNullOrWhiteSpace(_Token); }
}
static string _Token;
public static string Token {
get { return _Token; }
}
public static void SaveToken(string token)
{
_Token = token;
}
public static Action SuccessfulLoginAction
{
get {
return new Action (() => {
_NavPage.Navigation.PopModalAsync();
});
}
}
}
}
The first thing to notice is the GetMainPage() method. This tells the app which screen it should load first upon launching.
We also have a simple property and method for storing the Token that is returned from the auth service, as well as a simple IsLoggedIn property.
There's an Action property as well; something I stuck in here in order to have a way for the platform implementations to perform a Xamarin.Forms navigation action. More on this later.
You'll also notice some red in your IDE because we haven't created the ProfilePage class yet. So, let's do that.
Create a very simple ProfilePage class in the Xamarin.Forms PCL project. We're not even going to do anything fancy with it because that will depend on your particular need. For the sake of simplicity in this sample, it will contain a single label:
namespace OAuth2Demo.XForms
{
public class ProfilePage : BaseContentPage
{
public ProfilePage ()
{
Content = new Label () {
Text = "Profile Page",
VerticalOptions = LayoutOptions.CenterAndExpand,
HorizontalOptions = LayoutOptions.CenterAndExpand,
};
}
}
}
Again, you'll probably have some red in your IDE because we seem to be missing the BaseContentPage class. The sole purpose of the BaseContentPage class is to ensure that none of the app's screens can be displayed until the user has logged in. (In this simplified demo, we're just persisting the user info to memory, so you'll need to re-login every time the app is run. In a real-world app, you'd be storing the authenticated user info to the device's keychain, which would eliminate the need to login at each app start.)
Create a BaseContentPage class in the Xamarin.Forms PCL project:
namespace OAuth2Demo.XForms
{
public class BaseContentPage : ContentPage
{
protected override void OnAppearing ()
{
base.OnAppearing ();
if (!App.IsLoggedIn) {
Navigation.PushModalAsync(new LoginPage());
}
}
}
}
There's a few interesting things going on here:
We're overriding the OnAppearing() method, which is similar to the ViewWillAppear method in an iOS UIViewController. You can execute any code here that you'd like to have run immediately before the screen appears.
The only thing we're doing in this method is checking to see if the user is logged in. If they're not, then we perform a modal push to a class called LoginPage. If you're unfamiliar with the concept of a modal, it's simply a view that takes the user out of the normal application flow in order to perform some special task; in our case, to perform a login.
So, let's create the LoginPage class in the Xamarin.Forms PCL project:
namespace OAuth2Demo.XForms
{
public class LoginPage : ContentPage
{
}
}
Wait...why doesn't this class have a body???
Since we're using the Xamatin.Auth component (which does the job of building and presenting a web view that works with the provided OAuth2 info), we actually don't want any kind of implementation in our LoginPage class. I know that seems weird, but bear with me.
The LoginPageRenderer for iOS
Up until this point, we've been working solely in the Xamarin.Forms PCL project. But now we need to provide the platform-specific implementation of our LoginPage in the iOS project. This is where the concept of a Renderer comes in.
In Xamarin.Forms, when you want to provide platform-specific screens and controls (i.e. screens that do not derive their content from the abstract pages in the Xamarin.Forms PCL project), you do so with Renderers.
Create a LoginPageRenderer class in your iOS platform project:
[assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))]
namespace OAuth2Demo.XForms.iOS
{
public class LoginPageRenderer : PageRenderer
{
public override void ViewDidAppear (bool animated)
{
base.ViewDidAppear (animated);
var auth = new OAuth2Authenticator (
clientId: "", // your OAuth2 client id
scope: "", // the scopes for the particular API you're accessing, delimited by "+" symbols
authorizeUrl: new Uri (""), // the auth URL for the service
redirectUrl: new Uri ("")); // the redirect URL for the service
auth.Completed += (sender, eventArgs) => {
// We presented the UI, so it's up to us to dimiss it on iOS.
App.SuccessfulLoginAction.Invoke();
if (eventArgs.IsAuthenticated) {
// Use eventArgs.Account to do wonderful things
App.SaveToken(eventArgs.Account.Properties["access_token"]);
} else {
// The user cancelled
}
};
PresentViewController (auth.GetUI (), true, null);
}
}
}
}
There are important things to note:
The [assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))] line at the top (and importantly before the namespace declaration) is using the Xamarin.Forms DependencyService. It's not the most beautiful thing in the world because it's not IoC/DI, but whatever...it works. This is the mechanism that "maps" our LoginPageRenderer to the LoginPage.
This is the class in which we're actually using the Xamarin.Auth component. That's where the OAuth2Authenticator reference comes from.
Once the login is successful, we fire off a Xamarin.Forms navigation via App.SuccessfulLoginAction.Invoke();. This gets us back to the ProfilePage.
Since we're on iOS, we're doing all of our logic sinde of the ViewDidAppear() method.
The LoginPageRenderer for Android
Create a LoginPageRenderer class in your Android platform project. (Note that class name you're creating is identical to the one in the iOS project, but here in the Android project the PageRenderer inherits from Android classes instead of iOS classes.)
[assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))]
namespace OAuth2Demo.XForms.Android
{
public class LoginPageRenderer : PageRenderer
{
protected override void OnModelChanged (VisualElement oldModel, VisualElement newModel)
{
base.OnModelChanged (oldModel, newModel);
// this is a ViewGroup - so should be able to load an AXML file and FindView<>
var activity = this.Context as Activity;
var auth = new OAuth2Authenticator (
clientId: "", // your OAuth2 client id
scope: "", // the scopes for the particular API you're accessing, delimited by "+" symbols
authorizeUrl: new Uri (""), // the auth URL for the service
redirectUrl: new Uri ("")); // the redirect URL for the service
auth.Completed += (sender, eventArgs) => {
if (eventArgs.IsAuthenticated) {
App.SuccessfulLoginAction.Invoke();
// Use eventArgs.Account to do wonderful things
App.SaveToken(eventArgs.Account.Properties["access_token"]);
} else {
// The user cancelled
}
};
activity.StartActivity (auth.GetUI(activity));
}
}
}
Again, let's take a look at some interesting things:
The [assembly: ExportRenderer (typeof (LoginPage), typeof (LoginPageRenderer))] line at the top (and importantly before the namespace declaration) is using the Xamarin.Forms DependencyService. No difference here from the iOS version of LoginPageRenderer.
Again, this is where we're actually using the Xamarin.Auth component. That's where the OAuth2Authenticator reference comes from.
Just as with the iOS version, once the login is successful, we fire off a Xamarin.Forms navigation via App.SuccessfulLoginAction.Invoke();. This gets us back to the ProfilePage.
Unlike the iOS version, we're doing all of the logic inside of the OnModelChanged() method instead of the ViewDidAppear().
Here it is on iOS:
...and Android:
UPDATE:
I've also provided a detailed sample at my blog: http://www.joesauve.com/using-xamarin-auth-with-xamarin-forms/
You could consume either Xamarin.Social or Xamarin.Auth for that. It allows using the same api whatever the platform is.
As of now, those libs aren't PCL yet, but you still can consume them from a Shared Assets Project, or abstract the API you need in an interface and inject in with DependencyService or any other DI container.
I've created a sample project to show how to create a Facebook login using native Facebook component, not through a webview like the solutions suggested here.
You can check it out in this address:
https://github.com/IdoTene/XamarinFormsNativeFacebook
IOS 8: For those who are using #NovaJoe code and are stuck on view, add the code bellow to workaround:
bool hasShown;
public override void ViewDidAppear(bool animated)
{
if (!hasShown)
{
hasShown = true;
// the rest of #novaJoe code
}
}
Here's a good Xamarin.Forms authentication sample. The documentation in the code is nice. It uses a webview to render the login screen, but you can select what login type you want. It also saves a users token so he doesn't have to keep re-logging in.
https://github.com/rlingineni/Xamarin.Forms_Authentication
Another addition to #NovaJoe's code, on iOS8 with Facebook, you'd need to modify the Renderer class as below to close the View after successful authentication.
auth.Completed += (sender, eventArgs) => {
// We presented the UI, so it's up to us to dimiss it on iOS.
/*Importand to add this line */
DismissViewController (true, null);
/* */
if (eventArgs.IsAuthenticated) {
App.Instance.SuccessfulLoginAction.Invoke ();
// Use eventArgs.Account to do wonderful things
App.Instance.SaveToken (eventArgs.Account.Properties ["access_token"]);
} else {
// The user cancelled
}
};
The correct implementation for the Androids PageRenderer is:
using System;
using Android.App;
using Android.Content;
using OAuth2Demo.XForms.Android;
using Xamarin.Auth;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using XamarinAuth;
[assembly: ExportRenderer(typeof(LoginPage), typeof(LoginPageRenderer))]
namespace OAuth2Demo.XForms.Android
{
public class LoginPageRenderer : PageRenderer
{
public LoginPageRenderer(Context context) : base(context) { }
protected override void OnElementChanged(ElementChangedEventArgs<Page> e)
{
base.OnElementChanged(e);
// this is a ViewGroup - so should be able to load an AXML file and FindView<>
var activity = this.Context as Activity;
var auth = new OAuth2Authenticator(
clientId: "<Constants.clientId>", // your OAuth2 client id
scope: "<Constants.scope>", // the scopes for the particular API you're accessing, delimited by "+" symbols
authorizeUrl: new Uri("<Constants.authorizeUrl>"), // the auth URL for the service
redirectUrl: new Uri("<Constants.redirectUrl>")); // the redirect URL for the service
auth.Completed += (sender, eventArgs) =>
{
if (eventArgs.IsAuthenticated)
{
App.SuccessfulLoginAction.Invoke();
// Use eventArgs.Account to do wonderful things
App.SaveToken(eventArgs.Account.Properties["access_token"]);
}
else
{
// The user cancelled
}
};
activity.StartActivity(auth.GetUI(activity));
}
}
}