ToastView.cs

// Licence: MIT X11
// Note: This is an Objective-C to C# translation by using code from: http://code.google.com/p/toast-notifications-ios/
using MonoTouch.Foundation;
using MonoTouch.UIKit;
using System;
using System.Drawing;

namespace Tabasco.iOS.Dialog
{
    /// <summary>
    /// Usage:
    ///     ToastView view = new ToastView("Event added to your schedule", 1000);
    ///     view.SetGravity(ToastGravity.Bottom);
    ///     view.Show();
    /// </summary>
    public class ToastView
    {
        private const int MAX_TOAST_LINES = 5;  //Support for multilines toasts. Max 5 lines
        private const int TOAST_WITHD = 280; //Total withd of the toast rectangle
        private const int TOAST_LINE_HEIGHT = 30; //Line Height
        private const double FADE_OUT_DURATION = 1.0; //Fade out animation duration

        private ToastSettings toastSettings = new ToastSettings();

        private string text = null;
        private UIView view;
        private int offsetLeft = 0;
        private int offsetTop = 0;

        /// <summary>
        /// Initializes a new instance of the <see cref="ToastView"/> class.
        /// </summary>
        /// <param name="content">The toast text</param>
        /// <param name="duration">The toast duration.</param>
        public ToastView(string content, TimeSpan duration)
        {
            text = content;
            toastSettings.Duration = duration;
        }

        /// <summary>
        /// Sets the Toast notification gravity
        /// </summary>
        /// <param name="gravity">The position in the screen</param>
        /// <param name="OffSetLeft">Left offset</param>
        /// <param name="OffSetTop">Top offset</param>
        /// <returns>The ToasView. Use of Fluent API</returns>
        public ToastView SetGravity(ToastGravity gravity, int OffSetLeft = 0, int OffSetTop = 0)
        {
            toastSettings.Gravity = gravity;
            offsetLeft = OffSetLeft;
            offsetTop = OffSetTop;
            return this;
        }

        /// <summary>
        /// Sets the toast notification position in the screen ()
        /// </summary>
        /// <param name="Position">The toast position in the screen</param>
        /// <returns>The ToastView. Use of fluent API</returns>
        public ToastView SetPosition(PointF Position)
        {
            toastSettings.Position = new TPoint(Position.X, Position.Y);
            return this;
        }

        /// <summary>
        /// Shows the Toast Notification
        /// </summary>
        public void Show()
        {
            UIButton toast = UIButton.FromType(UIButtonType.Custom);
            view = toast;

            UIFont font = UIFont.SystemFontOfSize(12);

            //Multiline support
            int lineCount = Math.Min(MAX_TOAST_LINES, text.Split('\n').Length + 1);
            SizeF textSize = view.StringSize(text, font, new SizeF(TOAST_WITHD, TOAST_LINE_HEIGHT * lineCount));

            UILabel label = new UILabel(new RectangleF(0, 0, textSize.Width + 5, textSize.Height + 5));
            label.BackgroundColor = UIColor.Clear;
            label.TextColor = UIColor.White;
            label.Font = font;
            label.Text = text;
            label.Lines = 0;
            label.ShadowColor = UIColor.DarkGray;
            label.ShadowOffset = new SizeF(1, 1);

            toast.Frame = new RectangleF(0, 0, textSize.Width + 10, textSize.Height + 10);
            label.Center = new PointF(toast.Frame.Size.Width / 2, toast.Frame.Height / 2);
            toast.AddSubview(label);

            toast.BackgroundColor = UIColor.FromRGBA(0, 0, 0, 0.7f);
            toast.Layer.CornerRadius = 5;

            UIWindow window = UIApplication.SharedApplication.Windows[0];

            PointF point;

            if (toastSettings.Gravity == ToastGravity.Top)
            {
                point = new PointF(window.Frame.Size.Width / 2, (textSize.Height / 2) + 35);
            }
            else if (toastSettings.Gravity == ToastGravity.Bottom)
            {
                point = new PointF(window.Frame.Size.Width / 2, window.Frame.Size.Height - (textSize.Height / 2) - 35);
            }
            else if (toastSettings.Gravity == ToastGravity.Center)
            {
                point = new PointF(window.Frame.Size.Width / 2, window.Frame.Size.Height / 2);
            }
            else
            {
                point = new PointF(toastSettings.Position.X, toastSettings.Position.Y);
            }

            point = new PointF(point.X + offsetLeft, point.Y + offsetTop);
            toast.Center = point;
            window.AddSubview(toast);

            // Dismiss the toast if the user touches the toast rectablge
            toast.AllTouchEvents += delegate { HideToast(); };

            //Auto hide after toast duration expires
            NSTimer.CreateScheduledTimer(toastSettings.Duration.TotalSeconds, () => this.HideToast());
        }

        /// <summary>
        /// Hides the toast using a fade out animation
        /// </summary>
        private void HideToast()
        {
            //Create the fade out animation.
            UIView.Animate(FADE_OUT_DURATION, 0, UIViewAnimationOptions.TransitionNone,
               () =>
               {
                   //End status of the animation
                   this.view.Alpha = 0;
               },
               () =>
               {
                   //What happens when the animation ends
                   this.RemoveToast();
               }
               );
        }

        /// <summary>
        /// Removes the toast from the view
        /// </summary>
        private void RemoveToast()
        {
            view.RemoveFromSuperview();
        }
    }


    /// <summary>
    /// Toast Notification Settigns
    /// </summary>
    public class ToastSettings
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="ToastSettings"/> class.
        /// </summary>
        public ToastSettings()
        {
            this.Duration = TimeSpan.FromSeconds(1);
            this.Gravity = ToastGravity.Center;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="ToastSettings"/> class.
        /// </summary>
        /// <param name="duration">The toast duration.</param>
        /// <param name="gravity">The toast gravity.</param>
        public ToastSettings(TimeSpan duration, ToastGravity gravity = ToastGravity.Center)
        {
            this.Duration = duration;
            this.Gravity = gravity;
        }

        /// <summary>
        /// Gets or sets the toast duration
        /// </summary>
        /// <value>
        /// The duration.
        /// </value>
        public TimeSpan Duration
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the toast gravity (position in the view).
        /// </summary>
        /// <value>
        /// The gravity.
        /// </value>
        public ToastGravity Gravity
        {
            get;
            set;
        }

        /// <summary>
        /// Gets or sets the toast position.
        /// </summary>
        /// <value>
        /// The position.
        /// </value>
        public TPoint Position
        {
            get;
            set;
        }
    }

    /// <summary>
    /// Defines a Point.
    /// FPoint is not supported in Portable Class Libraries
    /// </summary>
    public class TPoint
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="TPoint"/> class.
        /// </summary>
        /// <param name="x">The x.</param>
        /// <param name="y">The y.</param>
        public TPoint(float x, float y)
        {
            this.X = x;
            this.Y = y;
        }

        /// <summary>
        /// Gets or sets the x.
        /// </summary>
        /// <value>
        /// The x.
        /// </value>
        public float X { get; set; }

        /// <summary>
        /// Gets or sets the y.
        /// </summary>
        /// <value>
        /// The y.
        /// </value>
        public float Y { get; set; }
    }

    /// <summary>
    /// The Toast Gravity enum
    /// </summary>
    public enum ToastGravity
    {
        Top = 0,
        Bottom = 1,
        Center = 2
    }
}

Adds fade out animation to the toasts + multi line support