Xamarin Toast Example

This is an example of a simple Xamarin Toast for Android and iOS.

Android has Toast built-in. iOS we have to add code to iOS project to do the same function.

It uses an interface service called IToast that its corresponding Dependency Service implementation is in Android and iOS.

NOTE: Got most of the code from LeoAndo's DependencyServiceToastSample

What are the items that make this work

Item	Description	Code Location
ToastHelper	Helper class to make the call to DependentServices	ToastExample->Helpers->ToastHelper.cs (Shared)
IToast	Main interface	ToastExample->Services->IToast.cs (Shared)
ToastAndroid	Android Service that is doing the work on Android	ToastExample.Android->Services->ToastAndroid.cs
ToastIOS	iOS Service that is doing the work on iOS	ToastExample.iOS->Services->ToastIOS.cs

How to register IToast service

Android

In Android code base,Open MainActivity.cs and add to OnCreate function before LoadApplication call

//Register Toast 
global::Xamarin.Forms.DependencyService.Register<ToastAndroid>();

iOS

No register is required due to at before namespace in ToastIOS.cs before

[assembly: Xamarin.Forms.Dependency(typeof(ToastIOS))]

Code

ToastHelper.cs

using System;
using ToastExample.Services;
using Xamarin.Essentials;
using Xamarin.Forms;

namespace ToastExample.Helpers
{
    public class ToastHelper
    {
        public static void Show(String Message)
        {
            MainThread.BeginInvokeOnMainThread(() =>
            {
                IToast iToast = DependencyService.Get<IToast>();
                if (iToast != null)
                {
                    iToast.Show(Message);
                }
            });
        }
    }
}

IToast.cs

namespace ToastExample.Services
{
    public interface IToast
    {
        void Show(string message);
    }
}

ToastAndroid.cs

using Android.App;
using Android.Widget;
using ToastExample.Services;

namespace ToastExample.Droid.Services
{
    public class ToastAndroid : IToast
    {
        Toast m_currentToast = null;


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

        public void Cancel()
        {
            if (m_currentToast != null)
            {
                m_currentToast.Cancel();
            }
        }
    }
}

ToastIOS.cs

using Foundation;
using System;
using UIKit;
using CoreGraphics;
using ToastExample.Services;
using ToastExample.iOS.Services;

[assembly: Xamarin.Forms.Dependency(typeof(ToastIOS))]
namespace ToastExample.iOS.Services
{
    public class ToastIOS : IToast
    {
        public static void Init()
        {

        }
        public void Show(string message)
        {
            var toast = new Toast();
            toast.Show(UIApplication.SharedApplication.KeyWindow.RootViewController.View, message);
        }
    }

    class Toast
    {
        // Toast View
        UIView _view;
        // Toast message
        UILabel _label;
        // Toast size
        int _margin = 30;
        int _height = 40;
        int _width = 200; // orginally was 150;

        NSTimer _timer = null;

        public Toast()
        {
            // create Toast View
            _view = new UIView(new CGRect(0, 0, 0, 0))
            {
                BackgroundColor = UIColor.Gray,
            };
            _view.Layer.CornerRadius = (nfloat)20.0;
            //  create Toast Label
            _label = new UILabel(new CGRect(0, 0, 0, 0))
            {
                TextAlignment = UITextAlignment.Center,
                TextColor = UIColor.White
            };
            _view.AddSubview(_label);

        }

        public void Show(UIView parent, string message)
        {
            if (_timer != null)
            {
                _timer.Invalidate();
                _view.RemoveFromSuperview();
            }

            _view.Alpha = (nfloat)0.7;

            _view.Frame = new CGRect(
                (parent.Bounds.Width - _width) / 2,
                parent.Bounds.Height - _height - _margin,
                _width,
                _height);

            _label.Frame = new CGRect(0, 0, _width, _height);
            _label.Text = message;

            parent.AddSubview(_view);


            var wait = 10;
            _timer = NSTimer.CreateRepeatingScheduledTimer(TimeSpan.FromMilliseconds(70), delegate
            {

                if (_view.Alpha <= 0)
                {
                    _timer.Invalidate();
                    _view.RemoveFromSuperview();
                }
                else
                {
                    if (wait > 0)
                    {
                        wait--;
                    }
                    else
                    {
                        _view.Alpha -= (nfloat)0.05;
                    }
                }
            });
        }
    }
}