From 3043fb73b50aafe398f42d341a387e7df0e16309 Mon Sep 17 00:00:00 2001
From: Andrei Nitescu <nitescua@yahoo.com>
Date: Thu, 10 Jan 2019 19:52:11 +0200
Subject: [PATCH] Map with ItemsSource and ItemTemplate (#4269) fixes #1708

---
 Xamarin.Forms.Controls/CoreGallery.cs              |   1 +
 .../GalleryPages/MapWithItemsSourceGallery.xaml    |  35 +++
 .../GalleryPages/MapWithItemsSourceGallery.xaml.cs | 155 +++++++++++
 .../Xamarin.Forms.Controls.csproj                  |  66 +++++
 Xamarin.Forms.Core.UnitTests/MapTests.cs           | 308 ++++++++++++++++++++-
 Xamarin.Forms.Maps/Map.cs                          | 114 ++++++++
 Xamarin.Forms.Maps/Pin.cs                          |   2 +-
 7 files changed, 679 insertions(+), 2 deletions(-)
 create mode 100644 Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml
 create mode 100644 Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml.cs

diff --git a/Xamarin.Forms.Controls/CoreGallery.cs b/Xamarin.Forms.Controls/CoreGallery.cs
index 0d8f322..daf969d 100644
--- a/Xamarin.Forms.Controls/CoreGallery.cs
+++ b/Xamarin.Forms.Controls/CoreGallery.cs
@@ -359,6 +359,7 @@ namespace Xamarin.Forms.Controls
 				new GalleryPageFactory(() => new ListRefresh(), "ListView.PullToRefresh"),
 				new GalleryPageFactory(() => new ListViewDemoPage(), "ListView Demo Gallery - Legacy"),
 				new GalleryPageFactory(() => new MapGallery(), "Map Gallery - Legacy"),
+				new GalleryPageFactory(() => new MapWithItemsSourceGallery(), "Map With ItemsSource Gallery - Legacy"),
 				new GalleryPageFactory(() => new MinimumSizeGallery(), "MinimumSize Gallery - Legacy"),
 				new GalleryPageFactory(() => new MultiGallery(), "Multi Gallery - Legacy"),
 				new GalleryPageFactory(() => new NavigationMenuGallery(), "NavigationMenu Gallery - Legacy"),
diff --git a/Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml b/Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml
new file mode 100644
index 0000000..e48b7a9
--- /dev/null
+++ b/Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
+			 xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+			 xmlns:map="clr-namespace:Xamarin.Forms.Maps;assembly=Xamarin.Forms.Maps"
+			 x:Class="Xamarin.Forms.Controls.GalleryPages.MapWithItemsSourceGallery">
+	<Grid>
+		<Grid.RowDefinitions>
+			<RowDefinition />
+			<RowDefinition Height="Auto" />
+		</Grid.RowDefinitions>
+		<map:Map ItemsSource="{Binding Places}"
+				 x:Name="_map">
+			<map:Map.ItemTemplate>
+				<DataTemplate>
+					<map:Pin Position="{Binding Position}"
+							 Address="{Binding Address}"
+							 Label="{Binding Description}" />
+				</DataTemplate>
+			</map:Map.ItemTemplate>
+		</map:Map>
+		<StackLayout Orientation="Horizontal"
+					 Grid.Row="1">
+			<Button Text="Add"
+					Command="{Binding AddPlaceCommand}" />
+			<Button Text="Remove"
+					Command="{Binding RemovePlaceCommand}" />
+			<Button Text="Clear"
+					Command="{Binding ClearPlacesCommand}" />
+			<Button Text="Update"
+					Command="{Binding UpdatePlacesCommand}" />
+			<Button Text="Replace"
+					Command="{Binding ReplacePlaceCommand}" />
+		</StackLayout>
+	</Grid>
+</ContentPage>
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml.cs b/Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml.cs
new file mode 100644
index 0000000..dd96aa3
--- /dev/null
+++ b/Xamarin.Forms.Controls/GalleryPages/MapWithItemsSourceGallery.xaml.cs
@@ -0,0 +1,155 @@
+using System;
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Linq;
+using System.Windows.Input;
+using Xamarin.Forms.Internals;
+using Xamarin.Forms.Maps;
+using Xamarin.Forms.Xaml;
+
+namespace Xamarin.Forms.Controls.GalleryPages
+{
+	[XamlCompilation(XamlCompilationOptions.Compile)]
+	public partial class MapWithItemsSourceGallery : ContentPage
+	{
+		static readonly Position startPosition = new Position(39.8283459, -98.5794797);
+
+		public MapWithItemsSourceGallery()
+		{
+			InitializeComponent();
+			BindingContext = new ViewModel();
+			_map.MoveToRegion(MapSpan.FromCenterAndRadius(startPosition, Distance.FromMiles(1200)));
+		}
+
+		[Preserve(AllMembers = true)]
+		class ViewModel
+		{
+			int _pinCreatedCount = 0;
+
+			readonly ObservableCollection<Place> _places;
+
+			public IEnumerable Places => _places;
+
+			public ICommand AddPlaceCommand { get; }
+			public ICommand RemovePlaceCommand { get; }
+			public ICommand ClearPlacesCommand { get; }
+			public ICommand UpdatePlacesCommand { get; }
+			public ICommand ReplacePlaceCommand { get; }
+
+			public ViewModel()
+			{
+				_places = new ObservableCollection<Place>() {
+					new Place("New York, USA", "The City That Never Sleeps", new Position(40.67, -73.94)),
+					new Place("Los Angeles, USA", "City of Angels", new Position(34.11, -118.41)),
+					new Place("San Francisco, USA", "Bay City ", new Position(37.77, -122.45))
+				};
+
+				AddPlaceCommand = new Command(AddPlace);
+				RemovePlaceCommand = new Command(RemovePlace);
+				ClearPlacesCommand = new Command(() => _places.Clear());
+				UpdatePlacesCommand = new Command(UpdatePlaces);
+				ReplacePlaceCommand = new Command(ReplacePlace);
+			}
+
+			void AddPlace()
+			{
+				_places.Add(NewPlace());
+			}
+
+			void RemovePlace()
+			{
+				if (_places.Any())
+				{
+					_places.Remove(_places.First());
+				}
+			}
+
+			void UpdatePlaces()
+			{
+				if (!_places.Any())
+				{
+					return;
+				}
+
+				double lastLatitude = _places.Last().Position.Latitude;
+
+				foreach (Place place in Places)
+				{
+					place.Position = new Position(lastLatitude, place.Position.Longitude);
+				}
+			}
+
+			void ReplacePlace()
+			{
+				if (!_places.Any())
+				{
+					return;
+				}
+
+				_places[_places.Count - 1] = NewPlace();
+			}
+
+			static class RandomPosition
+			{
+				static Random Random = new Random(Environment.TickCount);
+
+				public static Position Next()
+				{
+					return new Position(
+						latitude: Random.NextDouble() * 180 - 90,
+						longitude: Random.NextDouble() * 360 - 180);
+				}
+
+				public static Position Next(Position position, double latitudeRange, double longitudeRange)
+				{
+					return new Position(
+						latitude: position.Latitude + (Random.NextDouble() * 2 - 1) * latitudeRange,
+						longitude: position.Longitude + (Random.NextDouble() * 2 - 1) * longitudeRange);
+				}
+			}
+
+			Place NewPlace()
+			{
+				++_pinCreatedCount;
+
+				return new Place(
+					$"Pin {_pinCreatedCount}",
+					$"Desc {_pinCreatedCount}",
+					RandomPosition.Next(startPosition, 8, 19));
+			}
+		}
+
+		[Preserve(AllMembers = true)]
+		class Place : INotifyPropertyChanged
+		{
+			Position _position;
+
+			public event PropertyChangedEventHandler PropertyChanged;
+
+			public string Address { get; }
+
+			public string Description { get; }
+
+			public Position Position
+			{
+				get => _position;
+				set
+				{
+					if (!_position.Equals(value))
+					{
+						_position = value;
+						PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Position)));
+					}
+				}
+			}
+
+			public Place(string address, string description, Position position)
+			{
+				Address = address;
+				Description = description;
+				Position = position;
+			}
+		}
+	}
+}
\ No newline at end of file
diff --git a/Xamarin.Forms.Controls/Xamarin.Forms.Controls.csproj b/Xamarin.Forms.Controls/Xamarin.Forms.Controls.csproj
index ce3765f..8826b36 100644
--- a/Xamarin.Forms.Controls/Xamarin.Forms.Controls.csproj
+++ b/Xamarin.Forms.Controls/Xamarin.Forms.Controls.csproj
@@ -40,6 +40,72 @@
     <EmbeddedResource Include="GalleryPages\crimson.jpg" />
     <PackageReference Include="Newtonsoft.Json" Version="10.0.3" />
     <PackageReference Include="Xam.Plugin.DeviceInfo" Version="3.0.2" />
+    <Compile Update="GalleryPages\BindableLayoutGalleryPage.xaml.cs">
+      <DependentUpon>BindableLayoutGalleryPage.xaml</DependentUpon>
+    </Compile>
+    <Compile Update="GalleryPages\VisualStateManagerGalleries\OnPlatformExample.xaml.cs">
+      <DependentUpon>OnPlatformExample.xaml</DependentUpon>
+    </Compile>
+    <EmbeddedResource Update="GalleryPages\BindableLayoutGalleryPage.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\MapWithItemsSourceGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\TitleView.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\VisualStateManagerGalleries\ButtonDisabledStatesGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\VisualStateManagerGalleries\DatePickerDisabledStatesGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\VisualStateManagerGalleries\PickerDisabledStatesGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\VisualStateManagerGalleries\SearchBarDisabledStatesGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\VisualStateManagerGalleries\TimePickerDisabledStatesGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\VisualStateManagerGalleries\ValidationExample.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\XamlPage.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="ControlGalleryPages\BehaviorsAndTriggers.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\StyleXamlGallery.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\XamlNativeViews.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\MacTwitterDemo.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="HanselForms\MyAbout.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="HanselForms\BlogPage.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="HanselForms\TwitterPage.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="CompressedLayout.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="ControlGalleryPages\LayoutAddPerformance.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="GalleryPages\ControlTemplateXamlPage.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
   </ItemGroup>
   <Target Name="CreateControllGalleryConfig" BeforeTargets="Build">
     <CreateItem Include="blank.config">
diff --git a/Xamarin.Forms.Core.UnitTests/MapTests.cs b/Xamarin.Forms.Core.UnitTests/MapTests.cs
index 0d6888d..251e944 100644
--- a/Xamarin.Forms.Core.UnitTests/MapTests.cs
+++ b/Xamarin.Forms.Core.UnitTests/MapTests.cs
@@ -1,5 +1,8 @@
-using System;
 using NUnit.Framework;
+using System;
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.Linq;
 using Xamarin.Forms.Maps;
 
 namespace Xamarin.Forms.Core.UnitTests
@@ -143,5 +146,308 @@ namespace Xamarin.Forms.Core.UnitTests
 
 			Assert.False (signaled);
 		}
+
+		[Test]
+		public void TracksEmpty()
+		{
+			var map = new Map();
+
+			var itemsSource = new ObservableCollection<int>();
+			map.ItemsSource = itemsSource;
+			map.ItemTemplate = new DataTemplate();
+
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksAdd()
+		{
+			var itemsSource = new ObservableCollection<int>();
+
+			var map = new Map()
+			{
+				ItemsSource = itemsSource,
+				ItemTemplate = GetItemTemplate()
+			};
+
+			itemsSource.Add(1);
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksInsert()
+		{
+			var itemsSource = new ObservableCollection<int>();
+
+			var map = new Map()
+			{
+				ItemsSource = itemsSource,
+				ItemTemplate = GetItemTemplate()
+			};
+
+			itemsSource.Insert(0, 1);
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksRemove()
+		{
+			var itemsSource = new ObservableCollection<int>() { 0, 1 };
+
+			var map = new Map()
+			{
+				ItemsSource = itemsSource,
+				ItemTemplate = GetItemTemplate()
+			};
+
+			itemsSource.RemoveAt(0);
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+
+			itemsSource.Remove(1);
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksReplace()
+		{
+			var itemsSource = new ObservableCollection<int>() { 0, 1, 2 };
+
+			var map = new Map()
+			{
+				ItemsSource = itemsSource,
+				ItemTemplate = GetItemTemplate()
+			};
+
+			itemsSource[0] = 3;
+			itemsSource[1] = 4;
+			itemsSource[2] = 5;
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void ItemMove()
+		{
+			var itemsSource = new ObservableCollection<int>() { 0, 1 };
+
+			var map = new Map()
+			{
+				ItemsSource = itemsSource,
+				ItemTemplate = GetItemTemplate()
+			};
+
+			itemsSource.Move(0, 1);
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+
+			itemsSource.Move(1, 0);
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksClear()
+		{
+			var itemsSource = new ObservableCollection<int>() { 0, 1 };
+
+			var map = new Map()
+			{
+				ItemsSource = itemsSource,
+				ItemTemplate = GetItemTemplate()
+			};
+
+			itemsSource.Clear();
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksNull()
+		{
+			var map = new Map()
+			{
+				ItemTemplate = GetItemTemplate()
+			};
+
+			var itemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10));
+			map.ItemsSource = itemsSource;
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+
+			itemsSource = null;
+			map.ItemsSource = itemsSource;
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void TracksItemTemplate()
+		{
+			var map = new Map()
+			{
+				ItemTemplate = GetItemTemplate()
+			};
+
+			var itemsSource = new ObservableCollection<int>(Enumerable.Range(0, 3));
+			map.ItemsSource = itemsSource;
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+			foreach (Pin pin in map.Pins)
+			{
+				Assert.IsTrue(pin.Address == "Address");
+			}
+
+			map.ItemTemplate = GetItemTemplate("Address 2");
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+			foreach(Pin pin in map.Pins)
+			{
+				Assert.IsTrue(pin.Address == "Address 2");
+			}
+		}
+
+		[Test]
+		public void ItemsSourceTakePrecendenceOverPins()
+		{
+			var map = new Map()
+			{
+				ItemTemplate = GetItemTemplate()
+			};
+
+			map.Pins.Add(new Pin() { Label = "Label" });
+			map.Pins.Add(new Pin() { Label = "Label" });
+
+			var itemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10));
+			map.ItemsSource = itemsSource;
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		[Test]
+		public void ElementIsGarbageCollectedAfterItsRemoved()
+		{
+			var map = new Map()
+			{
+				ItemTemplate = GetItemTemplate()
+			};
+
+			// Create a view-model and bind the map to it
+			map.SetBinding(Map.ItemsSourceProperty, new Binding(nameof(MockViewModel.Items)));
+			map.BindingContext = new MockViewModel(new ObservableCollection<int>(Enumerable.Range(0, 10)));
+
+			// Set ItemsSource
+			var itemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10));
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+			itemsSource = null;
+
+			// Remove map from container
+			var pageRoot = new Grid();
+			pageRoot.Children.Add(map);
+			var page = new ContentPage() { Content = pageRoot };
+
+			var weakReference = new WeakReference(map);
+			pageRoot.Children.Remove(map);
+			map = null;
+
+			GC.Collect();
+			GC.WaitForPendingFinalizers();
+
+			Assert.IsFalse(weakReference.IsAlive);
+		}
+
+		[Test]
+		public void ThrowsExceptionOnUsingDataTemplateSelectorForItemTemplate()
+		{
+			var map = new Map();
+
+			var itemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10));
+			map.ItemsSource = itemsSource;
+
+			Assert.Throws(typeof(NotSupportedException), () => map.ItemTemplate = GetDataTemplateSelector());
+		}
+
+		[Test]
+		public void DontTrackAfterItemsSourceChanged()
+		{
+			var map = new Map()
+			{
+				ItemTemplate = GetItemTemplate()
+			};
+
+			var itemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10));
+			map.ItemsSource = itemsSource;
+			map.ItemsSource = new ObservableCollection<int>(Enumerable.Range(0, 10));
+
+			itemsSource.Add(11);
+			Assert.IsTrue(itemsSource.Count() == 11);
+		}
+
+		[Test]
+		public void WorksWithNullItems()
+		{
+			var map = new Map()
+			{
+				ItemTemplate = GetItemTemplate()
+			};
+
+			var itemsSource = new ObservableCollection<int?>(Enumerable.Range(0, 10).Cast<int?>());
+			itemsSource.Add(null);
+			map.ItemsSource = itemsSource;
+			Assert.IsTrue(IsMapWithItemsSource(itemsSource, map));
+		}
+
+		// Checks if for every item in the items source there's a corresponding pin
+		static bool IsMapWithItemsSource(IEnumerable itemsSource, Map map)
+		{
+			if (itemsSource == null)
+			{
+				return true;
+			}
+
+			if (map.ItemTemplate == null)
+			{
+				// If ItemsSource is set but ItemTemplate is not, there should not be any Pins
+				return !map.Pins.Any();
+			}
+
+			int i = 0;
+			foreach (object item in itemsSource)
+			{
+				// Pins collection order are not tracked, so just make sure a Pin for item exists
+				if (!map.Pins.Any(p => Equals(item, p.BindingContext)))
+				{
+					return false;
+				}
+
+				++i;
+			}
+
+			return map.Pins.Count == i;
+		}
+
+		static DataTemplate GetItemTemplate(string address = null)
+		{
+			return new DataTemplate(() => new Pin()
+			{
+				Address = address ?? "Address",
+				Label = "Label",
+				Position = new Position()
+			});
+		}
+
+		static DataTemplateSelector GetDataTemplateSelector()
+		{
+			return new TestDataTemplateSelector();
+		}
+
+		class TestDataTemplateSelector : DataTemplateSelector
+		{
+			readonly DataTemplate dt = GetItemTemplate();
+
+			protected override DataTemplate OnSelectTemplate(object item, BindableObject container)
+			{
+				return dt;
+			}
+		}
+
+		class MockViewModel
+		{
+			public IEnumerable Items { get; }
+			public MockViewModel(IEnumerable itemsSource)
+			{
+				Items = itemsSource;
+			}
+		}
 	}
 }
diff --git a/Xamarin.Forms.Maps/Map.cs b/Xamarin.Forms.Maps/Map.cs
index c717950..f881c19 100644
--- a/Xamarin.Forms.Maps/Map.cs
+++ b/Xamarin.Forms.Maps/Map.cs
@@ -18,6 +18,12 @@ namespace Xamarin.Forms.Maps
 
 		public static readonly BindableProperty HasZoomEnabledProperty = BindableProperty.Create("HasZoomEnabled", typeof(bool), typeof(Map), true);
 
+		public static readonly BindableProperty ItemsSourceProperty = BindableProperty.Create(nameof(IEnumerable), typeof(IEnumerable), typeof(Map), default(IEnumerable),
+			propertyChanged: (b, o, n) => ((Map)b).OnItemsSourcePropertyChanged((IEnumerable)o, (IEnumerable)n));
+
+		public static readonly BindableProperty ItemTemplateProperty = BindableProperty.Create(nameof(ItemTemplate), typeof(DataTemplate), typeof(Map), default(DataTemplate),
+			propertyChanged: (b, o, n) => ((Map)b).OnItemTemplatePropertyChanged((DataTemplate)o, (DataTemplate)n));
+
 		readonly ObservableCollection<Pin> _pins = new ObservableCollection<Pin>();
 		MapSpan _visibleRegion;
 
@@ -64,6 +70,18 @@ namespace Xamarin.Forms.Maps
 			get { return _pins; }
 		}
 
+		public IEnumerable ItemsSource
+		{
+			get { return (IEnumerable)GetValue(ItemsSourceProperty); }
+			set { SetValue(ItemsSourceProperty, value); }
+		}
+
+		public DataTemplate ItemTemplate
+		{
+			get { return (DataTemplate)GetValue(ItemTemplateProperty); }
+			set { SetValue(ItemTemplateProperty, value); }
+		}
+
 		[EditorBrowsable(EditorBrowsableState.Never)]
 		public void SetVisibleRegion(MapSpan value) => VisibleRegion = value;
 		public MapSpan VisibleRegion
@@ -107,5 +125,101 @@ namespace Xamarin.Forms.Maps
 			if (e.NewItems != null && e.NewItems.Cast<Pin>().Any(pin => pin.Label == null))
 				throw new ArgumentException("Pin must have a Label to be added to a map");
 		}
+
+		void OnItemsSourcePropertyChanged(IEnumerable oldItemsSource, IEnumerable newItemsSource)
+		{
+			if (oldItemsSource is INotifyCollectionChanged ncc)
+			{
+				ncc.CollectionChanged -= OnItemsSourceCollectionChanged;
+			}
+
+			if (newItemsSource is INotifyCollectionChanged ncc1)
+			{
+				ncc1.CollectionChanged += OnItemsSourceCollectionChanged;
+			}
+
+			_pins.Clear();
+			CreatePinItems();
+		}
+
+		void OnItemTemplatePropertyChanged(DataTemplate oldItemTemplate, DataTemplate newItemTemplate)
+		{
+			if (newItemTemplate is DataTemplateSelector)
+			{
+				throw new NotSupportedException($"You are using an instance of {nameof(DataTemplateSelector)} to set the {nameof(Map)}.{ItemTemplateProperty.PropertyName} property. Use an instance of a {nameof(DataTemplate)} property instead to set an item template.");
+			}
+
+			_pins.Clear();
+			CreatePinItems();
+		}
+
+		void OnItemsSourceCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
+		{
+			switch (e.Action)
+			{
+				case NotifyCollectionChangedAction.Add:
+					if (e.NewStartingIndex == -1)
+						goto case NotifyCollectionChangedAction.Reset;
+					foreach (object item in e.NewItems)
+						CreatePin(item);
+					break;
+				case NotifyCollectionChangedAction.Move:
+					if (e.OldStartingIndex == -1 || e.NewStartingIndex == -1)
+						goto case NotifyCollectionChangedAction.Reset;
+					// Not tracking order
+					break;
+				case NotifyCollectionChangedAction.Remove:
+					if (e.OldStartingIndex == -1)
+						goto case NotifyCollectionChangedAction.Reset;
+					foreach (object item in e.OldItems)
+						RemovePin(item);
+					break;
+				case NotifyCollectionChangedAction.Replace:
+					if (e.OldStartingIndex == -1)
+						goto case NotifyCollectionChangedAction.Reset;
+					foreach (object item in e.OldItems)
+						RemovePin(item);
+					foreach (object item in e.NewItems)
+						CreatePin(item);
+					break;
+				case NotifyCollectionChangedAction.Reset:
+					_pins.Clear();
+					break;
+			}
+		}
+
+		void CreatePinItems()
+		{
+			if (ItemsSource == null || ItemTemplate == null)
+			{
+				return;
+			}
+
+			foreach (object item in ItemsSource)
+			{
+				CreatePin(item);
+			}
+		}
+
+		void CreatePin(object newItem)
+		{
+			if (ItemTemplate == null)
+			{
+				return;
+			}
+
+			var pin = (Pin)ItemTemplate.CreateContent();
+			pin.BindingContext = newItem;
+			_pins.Add(pin);
+		}
+
+		void RemovePin(object itemToRemove)
+		{
+			Pin pinToRemove = _pins.FirstOrDefault(pin => pin.BindingContext?.Equals(itemToRemove) == true);
+			if (pinToRemove != null)
+			{
+				_pins.Remove(pinToRemove);
+			}
+		}
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Maps/Pin.cs b/Xamarin.Forms.Maps/Pin.cs
index 43f7b75..ca959ca 100644
--- a/Xamarin.Forms.Maps/Pin.cs
+++ b/Xamarin.Forms.Maps/Pin.cs
@@ -3,7 +3,7 @@ using System.ComponentModel;
 
 namespace Xamarin.Forms.Maps
 {
-	public class Pin : BindableObject
+	public class Pin : Element
 	{
 		public static readonly BindableProperty TypeProperty = BindableProperty.Create("Type", typeof(PinType), typeof(Pin), default(PinType));
 
-- 
2.7.4