Toast equivalent for Xamarin Forms

问题

Is there any way using Xamarin Forms (not Android or iOS specific) to have a pop-up, like Android does with Toast, that needs no user interaction and goes away after a (short) period of time?

From searching around all I'm seeing are alerts that need user clicks to go away.

回答1:

There is a simple solution for this. By using the DependencyService you can easily get the Toast-Like approach in both Android and iOS.

Create an interface in your common package.

public interface IMessage
{
    void LongAlert(string message);
    void ShortAlert(string message);
}

Android section

[assembly: Xamarin.Forms.Dependency(typeof(MessageAndroid))]
namespace Your.Namespace
{
    public class MessageAndroid : IMessage
    {
        public void LongAlert(string message)
        {
            Toast.MakeText(Application.Context, message, ToastLength.Long).Show();
        }

        public void ShortAlert(string message)
        {
            Toast.MakeText(Application.Context, message, ToastLength.Short).Show();
        }
    }
}

iOS section

In iOs there is no native solution like Toast, so we need to implement our own approach.

[assembly: Xamarin.Forms.Dependency(typeof(MessageIOS))]
namespace Bahwan.iOS
{
    public class MessageIOS : IMessage
    {
        const double LONG_DELAY = 3.5;
        const double SHORT_DELAY = 2.0;

        NSTimer alertDelay;
        UIAlertController alert;

        public void LongAlert(string message)
        {
            ShowAlert(message, LONG_DELAY);
        }
        public void ShortAlert(string message)
        {
            ShowAlert(message, SHORT_DELAY);
        }

        void ShowAlert(string message, double seconds)
        {
            alertDelay = NSTimer.CreateScheduledTimer(seconds, (obj) =>
            {
                dismissMessage();
            });
            alert = UIAlertController.Create(null, message, UIAlertControllerStyle.Alert);
            UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(alert, true, null);
        }

        void dismissMessage()
        {
            if (alert != null)
            {
                alert.DismissViewController(true, null);
            }
            if (alertDelay != null)
            {
                alertDelay.Dispose();
            }
        }
    }
}

Please note that in each platform, we have to register our classes with DependencyService.

Now you can access out Toast service in anywhere in our project.

DependencyService.Get<IMessage>().ShortAlert(string message); 
DependencyService.Get<IMessage>().LongAlert(string message);

回答2:

Here's a version of Alex Chengalan's iOS code that avoids the UI sticking when multiple messages are shown...

public class MessageIOS : IMessage
    {
        const double LONG_DELAY = 3.5;
        const double SHORT_DELAY = 0.75;

        public void LongAlert(string message)
        {
            ShowAlert(message, LONG_DELAY);
        }

        public void ShortAlert(string message)
        {
            ShowAlert(message, SHORT_DELAY);
        }

        void ShowAlert(string message, double seconds)
        {
            var alert = UIAlertController.Create(null, message, UIAlertControllerStyle.Alert);

            var alertDelay = NSTimer.CreateScheduledTimer(seconds, obj =>
            {
                DismissMessage(alert, obj);
            });

            UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(alert, true, null);
        }

        void DismissMessage(UIAlertController alert, NSTimer alertDelay)
        {
            if (alert != null)
            {
                alert.DismissViewController(true, null);
            }

            if (alertDelay != null)
            {
                alertDelay.Dispose();
            }
        }
    }

回答3:

Adding to Alex's answer, here's the UWP variant:

public class Message : IMessage {
  private const double LONG_DELAY = 3.5;
  private const double SHORT_DELAY = 2.0;

  public void LongAlert(string message) =>
    ShowMessage(message, LONG_DELAY);

  public void ShortAlert(string message) =>
    ShowMessage(message, SHORT_DELAY);

  private void ShowMessage(string message, double duration) {
    var label = new TextBlock {
      Text = message,
      Foreground = new SolidColorBrush(Windows.UI.Colors.White),
      HorizontalAlignment = HorizontalAlignment.Center,
      VerticalAlignment = VerticalAlignment.Center,
    };
    var style = new Style { TargetType = typeof(FlyoutPresenter) };
    style.Setters.Add(new Setter(Control.BackgroundProperty, new SolidColorBrush(Windows.UI.Colors.Black)));
    style.Setters.Add(new Setter(FrameworkElement.MaxHeightProperty, 1));
    var flyout = new Flyout {
      Content = label,
      Placement = FlyoutPlacementMode.Full,
      FlyoutPresenterStyle = style,
    };

    flyout.ShowAt(Window.Current.Content as FrameworkElement);

    var timer = new DispatcherTimer { Interval = TimeSpan.FromSeconds(duration) };
    timer.Tick += (sender, e) => {
      timer.Stop();
      flyout.Hide();
    };
    timer.Start();
  }
}

Coloring and styling is up to you, the MaxHeightis actually required to keep the height at the minimum.

回答4:

Here is a code snippet that I am using to show the toast in Xamarin.iOS

  public void ShowToast(String message, UIView view)
    {
        UIView residualView = view.ViewWithTag(1989);
        if (residualView != null)
            residualView.RemoveFromSuperview();

        var viewBack = new UIView(new CoreGraphics.CGRect(83, 0, 300, 100));
        viewBack.BackgroundColor = UIColor.Black;
        viewBack.Tag = 1989;
        UILabel lblMsg = new UILabel(new CoreGraphics.CGRect(0, 20, 300, 60));
        lblMsg.Lines = 2;
        lblMsg.Text = message;
        lblMsg.TextColor = UIColor.White;
        lblMsg.TextAlignment = UITextAlignment.Center;
        viewBack.Center = view.Center;
        viewBack.AddSubview(lblMsg);
        view.AddSubview(viewBack);
        roundtheCorner(viewBack);
        UIView.BeginAnimations("Toast");
        UIView.SetAnimationDuration(3.0f);
        viewBack.Alpha = 0.0f;
        UIView.CommitAnimations();
    }

回答5:

We'd normally use Egors Toasts plugin, but as it requires permissions on iOS for a current project we've gone a different route using Rg.Plugins.Popup nuget (https://github.com/rotorgames/Rg.Plugins.Popup).

I wrote a basic xaml/cs page of type PopupPage,

<?xml version="1.0" encoding="utf-8" ?>
<popup:PopupPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:popup="clr-namespace:Rg.Plugins.Popup.Pages;assembly=Rg.Plugins.Popup"
         x:Class="YourApp.Controls.ToastPage">
...

and have it created by a service, whose interface you register at app start or use Xamarin.Forms.DependencyService to fetch the service would be viable too.

The service news up the PopupPage derived page, and does

await PopupNavigation.PushAsync(newToastPage);
await Task.Delay(2000);
await PopupNavigation.PopAllAsync();

The Popup page can be dismissed by the user by tapping outside the page display (assuming it hasn't filled the screen).

This seems to work happily on iOS/Droid, but I'm open to correction if anyone knows what this is a risky way of doing it.

回答6:

@MengTim, to fix the multiple toast issue in @alex-chengalan's solution, I simply wrapped everything within ShowAlert() with a check to see if alert and alertDelay are null, then within DismissMessage, nulled out alert and alertDelay.

void ShowAlert(string message, double seconds)
    {
        if(alert == null && alertDelay == null) {
            alertDelay = NSTimer.CreateScheduledTimer(seconds, (obj) =>
            {
                DismissMessage();
            });
            alert = UIAlertController.Create(null, message, UIAlertControllerStyle.Alert);
            UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(alert, true, null);
        }
    }

    void DismissMessage()
    {
        if (alert != null)
        {
            alert.DismissViewController(true, null);
            alert = null;
        }
        if (alertDelay != null)
        {
            alertDelay.Dispose();
            alertDelay = null;
        }
    }

That seemed to at least clear up the UI hang, if you are looking for a quick fix. I was trying to display the toast on navigation to a new page, and believe that the PresentViewController being set was essentially cancelling out my navigation. Sorry I did not comment within the thread, my reputation is too low :(

回答7:

You can use Acr.UserDialogs Package from nuget and code like below,

Acr.UserDialogs.UserDialogs.Instance.Toast(Message, new TimeSpan(3));

回答8:

You can use IUserDialog NuGet and simply use it's toastAlert

var toastConfig = new ToastConfig("Toasting...");
toastConfig.SetDuration(3000);
toastConfig.SetBackgroundColor(System.Drawing.Color.FromArgb(12, 131, 193));

UserDialogs.Instance.Toast(toastConfig);

回答9:

There is no built-in mechanism in Forms, but this nuget package supplies something similar

https://github.com/EgorBo/Toasts.Forms.Plugin

Note: These are not Android style toasts as requested in the question but UWP style toasts which are system wide notifications.

回答10:

This is my improved ShowAlert version of Ian Warburton's version to ensure that the toast is displayed even on popup page. Furthermore, the toast is dissmissed if the user click outside the toast. I used UIAlertControllerStyle.ActionSheet that look likes toast but it also work with UIAlertControllerStyle.Alert

    void ShowAlert(string message, double seconds)
    {
        var alert = UIAlertController.Create(null, message, UIAlertControllerStyle.ActionSheet);

        var alertDelay = NSTimer.CreateScheduledTimer(seconds, obj =>
        {
            DismissMessage(alert, obj);
        });

        var viewController = UIApplication.SharedApplication.KeyWindow.RootViewController;
        while (viewController.PresentedViewController != null)
        {
            viewController = viewController.PresentedViewController;
        }
        viewController.PresentViewController(alert, true, () =>
        {
            UITapGestureRecognizer tapGesture = new UITapGestureRecognizer(_ => DismissMessage(alert, null));
            alert.View.Superview?.Subviews[0].AddGestureRecognizer(tapGesture);
        });
    }

I hope this will help someone !

回答11:

The iOS answers above worked for me but for one little problem -- a warning: Attempt to present UIAlertController ... whose view is not in the window hierarchy!

After some search, I came across this unrelated answer which helped. The poster commented "This looks stupid but works", which is right on both counts.

So, I modified the ShowAlert() function above with these lines, which seem to work:

    var rootVC = UIApplication.SharedApplication.KeyWindow.RootViewController;
    while ( rootVC.PresentedViewController != null) {
        rootVC = rootVC.PresentedViewController;
    }
    rootVC.PresentViewController( alert, true, null);

回答12:

For UWP

public void ShowMessageFast(string message)
    {
        ToastNotifier ToastNotifier = ToastNotificationManager.CreateToastNotifier();
        Windows.Data.Xml.Dom.XmlDocument toastXml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastText02);
        Windows.Data.Xml.Dom.XmlNodeList toastNodeList = toastXml.GetElementsByTagName("text");
        toastNodeList.Item(0).AppendChild(toastXml.CreateTextNode("Test"));
        toastNodeList.Item(1).AppendChild(toastXml.CreateTextNode(message));
        Windows.Data.Xml.Dom.IXmlNode toastNode = toastXml.SelectSingleNode("/toast");
        Windows.Data.Xml.Dom.XmlElement audio = toastXml.CreateElement("audio");
        audio.SetAttribute("src", "ms-winsoundevent:Notification.SMS");

        ToastNotification toast = new ToastNotification(toastXml);
        toast.ExpirationTime = DateTime.Now.AddSeconds(4);
        ToastNotifier.Show(toast);
    }

回答13:

Check plugin.toast v 2.1.2 available for android, iOS and UWP

回答14:

I would recommend Plugin.Toast library from nuget. It works well.

CrossToastPopUp.Current.ShowToastMessage("my toast message");

回答15:

You can use DisplayAlert("", "", "", "" );

来源：https://stackoverflow.com/questions/35279403/toast-equivalent-for-xamarin-forms