DisplayAlert Xamarim forms - xamarin

Question

I Have this:
var accept = await DisplayAlert("Title", "ask", "yes", "not");
I would like this displayalert to be visible for 5 seconds if the user does not choose any option the displayalert disappears
how can i do this?

Answer 1

Welcome to SO !
Unfortunately , Xamarin Forms not provides some like Dismiss method for alert windown . However , we can use other ways to achieve that . Such as using Xamarin.Forms DependencyService .
First , we can create a IShowAlertService interface in xamarin forms :
public interface IShowAlertService
{
Task<bool> ShowAlert(string title,string message,string ok, string cancel);
}
Next in iOS , Create its implement class :
[assembly: Dependency(typeof(ShowAlertService))]
namespace XamarinTableView.iOS
{
class ShowAlertService : IShowAlertService
{
TaskCompletionSource<bool> taskCompletionSource;
public Task<bool> ShowAlert(string title, string message, string ok, string cancel)
{
taskCompletionSource = new TaskCompletionSource<bool>();
var okCancelAlertController = UIAlertController.Create(title, message, UIAlertControllerStyle.Alert);
//Add Actions
okCancelAlertController.AddAction(UIAlertAction.Create(ok, UIAlertActionStyle.Default, alert => {
Console.WriteLine("Okay was clicked");
taskCompletionSource.SetResult(true);
}));
okCancelAlertController.AddAction(UIAlertAction.Create(cancel, UIAlertActionStyle.Cancel, alert => {
Console.WriteLine("Cancel was clicked");
taskCompletionSource.SetResult(true);
}));
UIWindow window = UIApplication.SharedApplication.KeyWindow;
var viewController = window.RootViewController;
//Present Alert
viewController.PresentViewController(okCancelAlertController, true, null);
Device.StartTimer(new TimeSpan(0, 0, 3), () =>
{
taskCompletionSource.SetResult(false);
Device.BeginInvokeOnMainThread(() =>
{
okCancelAlertController.DismissViewController(true,null);
// interact with UI elements
Console.WriteLine("Auto Dismiss");
});
return false; // runs again, or false to stop
});
return taskCompletionSource.Task;
}
}
And in Android , also do that :
[assembly: Dependency(typeof(ShowAlertService))]
namespace XamarinTableView.Droid
{
class ShowAlertService : IShowAlertService
{
TaskCompletionSource<bool> taskCompletionSource;
public Task<bool> ShowAlert(string title, string message, string ok, string cancel)
{
taskCompletionSource = new TaskCompletionSource<bool>();
Android.App.AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.Instance);
AlertDialog alert = dialog.Create();
alert.SetTitle("Title");
alert.SetMessage("Complex Alert");
alert.SetButton("OK", (c, ev) =>
{
// Ok button click task
Console.WriteLine("Okay was clicked");
taskCompletionSource.SetResult(true);
});
alert.SetButton2("CANCEL", (c, ev) => {
Console.WriteLine("Cancel was clicked");
taskCompletionSource.SetResult(false);
});
alert.Show();
Device.StartTimer(new TimeSpan(0, 0, 3), () =>
{
if (taskCompletionSource.Equals(null))
taskCompletionSource.SetResult(false);
Device.BeginInvokeOnMainThread(() =>
{
alert.Dismiss();
// interact with UI elements
Console.WriteLine("Auto Dismiss");
});
return false; // runs again, or false to stop
});
return taskCompletionSource.Task;
}
}
}
Here in Android , need to create a static Instance in MainActivity . Becasue we need to use it in ShowAlertService :
public class MainActivity : FormsAppCompatActivity
{
internal static MainActivity Instance { get; private set; }
protected override void OnCreate(Bundle savedInstanceState)
{
// ...
Instance = this;
}
//...
}
Now in Xamarin Forms , we can involke it as follow :
private async void Button_Clicked(object sender, EventArgs e)
{
bool value = await DependencyService.Get<IShowAlertService>().ShowAlert("Alert", "You have been alerted", "OK", "Cancel");
Console.WriteLine("Value is : "+value);
}
The effect as follow :