Im using xamarin forms 2.3.4.247 shared project. In my login page im navigating my page to another. while this page is rendering im showing a Activity Indicator in Main Page. But unfortunately Activity Indicator Stucks And After A couple of seconds the second page loads.ive tried these codes below and i got nothing.All of these codes are running into an async command.im testing my app in actual device on android platform.
1
activityIndicator.IsRunnig=true;
new System.Threading.Thread(new System.Threading.ThreadStart(() =>
{
Navigation.PushAsync(new DeviceLoginView());
})).Start();
2
activityIndicator.IsRunnig=true;
Device.BeginInvokeOnMainThread(async () =>
{
await Navigation.PushAsync(new DeviceLoginView());
});
3
activityIndicator.IsRunnig=true;
await Navigation.PushAsync(new DeviceLoginView());
That issue is because your activity indicator is in the UI of the old page not on the new page, so when you do the Push the old page is not longer displaying.
For have the result you want, you can use this plugin for keep having the loading during the transition
https://github.com/aritchie/userdialogs
i Finally was able to make this issue right.
you can do all your asynchronous jobs in a Task.Run() method to run all of them in a new thread and NOT in the UI thread
Related
The application I'm currently working on requires data to be retrieved from a web service during app startup that roughly takes 1.5 seconds. After the data is retrieved, it needs to be displayed on the MainPage and that is another 1.5 - 2 seconds since the data is mostly URLs of images that have to be displayed, in my case, using ffimageloading library; which means actually downloading those images first to be displayed.
I have splash startup screens for both Android and iOS implemented separately in platform projects but splash screen only stays up for the amount of time Xamarin Forms needs to load and afterwards disappears not waiting for my actual model to load from the web service. I have searched for solutions to extend the splash screen duration and mostly every solution I have read involves creating another splash screen page, loading page if you will, that is already controlled in PCL project but having two separate splash loading screens just seams not feasible to me at the moment.
So I was wondering, how would one load the initial model in platform projects, during the actual splash screen, and then later pass it to PCL project when Xamarin Forms has finished initialization, presumably to App.xaml.cs 's App() constructor function?
There is no code or enough details so I am assuming this is what you want to do.
Call the APIs asynchrnously , till then show splash screen.
Before assigning MainPage in your App.xaml.cs you should call these APIs asynchronously with await and then you use the same for binding of your mainpage
public App()
{
InitializeComponent();
//do all my prefetch stuff for app initialization.
// API and what not
var viewmodel = new AppMainViewModel();
await viewmodel.CallFooFetchAsync();
await viewmodel.BlahBlahAsync();
MainPage = new NavigationPage(new AppMainPage(viewmodel));
}
In Page
public AppMainPage(AppMainViewModel vm)
{
BindingContext =vm;
}
So by the time page loads it has all the data handy.
You can explore adding this code in OnAppearing of the page.
Note that the concept of default Splash screen is just to show an image(with different theme in Android) and setting image in iOS. You need to have conventional UI technically its not splash screen anymore.
Alternatively you can get shared project handle in native
Android Sp
protected override void OnCreate(Bundle bundle)
{
...
var app = new App(); //this will be shared project App object
Device.BeginInvokeOnMainThread(async () => await app.DoPrefetchStuffFirst()); //API calls if needed in this async method
//then
LoadApplicationm(app)
}
You can do similar thing in iOS AppDelegate
And if you call native specific methods in platforms (may be for API calls) then you would use DependencyService feature , that will pass it to shared project or Custom renderer based on where you want to use it.
I'm running into an issue on android where our TimePicker and DatePicker stay visible when we navigate OnPause(). We need to redirect our users back to the login screen when they background the application, but if the TimePicker or DatePicker is active when they do this it stays on the screen. It appears above the login screen and pressing cancel or ok crashes the app.
We are hooking into the native android lifecycle events (not just using Xamarins built in hooks) and we redirect OnResume(). I've tested this in a barebones app though and it still happens OnPause().
Here is our TimePicker causing us the issue:
<TimePicker x:Name="VitalTimePicker" HorizontalOptions="Fill" VerticalOptions="Fill" IsVisible="false" PropertyChanged="OnTimePickerPropertyChanged"/>
And here is an example of changing screens on a lifecycle event:
protected override void OnSleep()
{
App.Current.MainPage = new NavigationPage(new NotesPage());
}
Any ideas? I was thinking of clearing the Pickers but I can't seem to find how to do that
Edit
Just to add a little more context
The Application class (app.xaml.cs) has lifecycle hooks that we use to catch when our users background the app. In here we call MainPage = new NavigationPage(new LoginPage()); which takes the app back to the login page.
I've added
protected override void OnDisappearing()
{
VitalTimePicker.Unfocus();
VitalDatePicker.Unfocus();
}
to the view i'm working from and it seems to be called when we background the application, but for some reason the TimePicker is staying on the screen when our login page pops up again.
You can programmatically close DatePickers and TimePickers using the method Unfocus(). I'd recommend closing them before you call the next page, as I don't know if they will be able to be referenced and closed after the other screen has been initialized.
Create a method that calls VitalTimePicker.Unfocus() and the same for any other picker you have, and call this method before changing to login screen and you should be good to go.
I need to refresh the application when push notification came at background. without opening push notification UI is not affecting .
Have anyone know how to update the application when its minimized where new update came. I have read Background fetch with perform fetch in xamarin forms but didn't get sufficient info anyone help please... Thanks.
UI actions must be performed on UI thread. If you want to make change on ui in background then you need to do it in MainThread like below:
Device.BeginInvokeOnMainThread (() => {
labelNotificationCount.Text = "1";
});
For more information, click here
We are facing a strange issue. Not sure if it is design flaw of the existing application. Your help/suggestion is appreciated.
We have a Xamarin.forms app. Targeted both for iOS and Android.
Problem is coming mainly in Android app.
Application flow:
once we logout from the application, app opens an logout activity and delete user info and other data.
opens a new activity for login which contains client SSO implementation
on successful login, app is setting user info and fetch data from web service.
then it calls LoadApplication method so that flow comes back in main application
Now if user perform logout/login several times, its opening a new application instance by calling LoadApplication method and then displaying home screen
So when user is tapping back button in home page, app is not closing and displays previous instance of same application.
User need to press back button several times (depending how many time user perform logout-login).
Is there any goodway to stop this?
Can we close current instance of the application before LoadApplication being called?
Stuck for a long time.
I'd try to avoid to call LoadApplication more then once. You should control the navigation stack.
Given you are on the LogoutPage
remove all views via PopToRootAsync
show the LoginPage
await Navigation.PopToRootAsync(false);
await Navigation.PushAsync(new LoginPage(), true);
This blog post may be worth a reading: https://jfarrell.net/2015/01/22/understanding-xamarin-forms-navigation/
Kindly try this.
https://stackoverflow.com/a/36885388/1941942
[Activity (NoHistory = true)]
public class LoginActivity : Activity { }
The saving instance error has gone a while after I implement it on MainActivity.
I am working on facebook authentication in a Xamarin forms app and want to use "native" login on each device.
The Facebook SDK (by Xamarin) is not designed for forms since it requires passing in an Android activity that implements some specific interfaces.
However; I was able to get the UI to display using a custom page renderer and then in that renderer calling StartActitivty with an activity that uses the exact implementation described in the Facebook SDK getting started. https://components.xamarin.com/view/facebookandroid
So far everything works perfect. The android app starts, xamarin forms kicks in, the custom page renderer is loaded the login android activity starts and the user logs in with facebook and we get to the console.writeline below.
So, how do I dismiss this intent or otherwise get back to xamarin forms?
Do I:
Dismiss this intent? - if so then what?
Inject something to "reset" the main page?
Other?
public void OnCompleted (Xamarin.Facebook.Model.IGraphUser user, Response response)
{
//TODO: show user details with welcome and button that takes them to main app.
//TODO: switch back to xam forms from here on out.
//TODO: figure out how to change the `main` activity to xam forms.
// 'Me' request callback
if (user != null) {
//How do I get back to Xamarin forms from here?
Console.WriteLine ("GOT USER: " + user.Name);
} else {
Console.WriteLine ("Failed to get 'me'!");
}
}
You should call Finish();
Anyway, if you want to see exactly how I did it, you can check it here:
https://github.com/IdoTene/XamarinFormsNativeFacebook