blocks|key|33170|text|我不认为Pins是Map上的可绑定属性，你可能想在Xamarin的Uservoice或fourm这里提交特性请求：http://forums.xamarin.com/discussion/31273/|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|33171|entityMap|0|LINK|mutability|MUTABLE|url|http://xamarin.uservoice.com/forums/258559-xamarin-forms-suggestions|1|http://forums.xamarin.com/discussion/31273/^0|4|4|9|3|X|9|0|1L|17|1|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]|$9|S|A|T|B|C]]|D|@$9|U|A|V|1|W]|$9|X|A|Y|1|Z]]|E|$]]|$1|F|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]|N|$5|I|J|K|E|$L|O]]]]

I don't think <code>Pins</code> is a bindable property on <code>Map</code>, you may want to file feature request at Xamarin's <a href="http://xamarin.uservoice.com/forums/258559-xamarin-forms-suggestions" rel="nofollow">Uservoice</a> or the fourm here: <a href="http://forums.xamarin.com/discussion/31273/" rel="nofollow">http://forums.xamarin.com/discussion/31273/</a>

blocks|key|4540443|text|这并不理想，但您可以在后面的代码中侦听属性更改事件，然后从那里应用更改。这有点手动，但它是可行的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4540444|((ViewModels.YourViewModel)BindingContext).PropertyChanged+%2B=+yourPropertyChanged;|code-block|syntax|javascript|4540445|然后定义"yourPropertyChanged“方法|4540446|private+void+yourPropertyChanged(object+sender,+PropertyChangedEventArgs+e)
{
++++if(e.PropertyName+==+"YourPropertyName")
++++{
++++++++var+position+=+new+Position(37.79762,+-122.40181);
++++++++Map.MoveToRegion(new+MapSpan(position,+0.01,+0.01));
++++++++Map.Pins.Add(new+Pin
++++++++{
++++++++++++Label+=+"Xamarin",
++++++++++++Position+=+position
++++++++});
++++}
}|4540447|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

It is not ideal, but you could listen for the property changed event in the code behind and then apply the change from there. Its a bit manual, but it is doable.

<pre><code>((ViewModels.YourViewModel)BindingContext).PropertyChanged += yourPropertyChanged;
</code></pre>

And then define the "yourPropertyChanged" method

<pre><code>private void yourPropertyChanged(object sender, PropertyChangedEventArgs e)
{
 if(e.PropertyName == "YourPropertyName")
 {
 var position = new Position(37.79762, -122.40181);
 Map.MoveToRegion(new MapSpan(position, 0.01, 0.01));
 Map.Pins.Add(new Pin
 {
 Label = "Xamarin",
 Position = position
 });
 }
}
</code></pre>

blocks|key|4540494|text|如果您不想打破MVVM模式，同时仍然能够从ViewModel访问Map对象，那么您可以使用ViewModel中的属性公开Map实例，并从视图中绑定到它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4540495|您的代码结构应如下所示。|4540496|ViewModel：|4540497|using+Xamarin.Forms.Maps;

namespace+YourApp.ViewModels
{
++++public+class+MapViewModel
++++{
++++++++public+MapViewModel()
++++++++{
++++++++++++Map+=+new+Map();
++++++++}

++++++++public+Map+Map+{+get;+private+set;+}
++++}
}|code-block|syntax|javascript|4540498|视图(在本例中我使用的是ContentPage，但您可以使用您喜欢的任何内容)：|offset|length|style|CODE|4540499|<?xml+version="1.0"+encoding="utf-8"+?>
<ContentPage+xmlns="http://xamarin.com/schemas/2014/forms"
+++++++++++++xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+++++++++++++x:Class="YourApp.Views.MapView">
++++<ContentPage.Content>
++++++++++++++++
++++++++++++++++<ContentView+Content="{Binding+Map}"/>
++++</ContentPage.Content>
</ContentPage>|4540500|我没有说明是如何实现的，但是上面的代码片段只有在ViewModel是视图的BindingContext时才能工作。|4540501|entityMap^0|0|0|0|0|C|B|0|0|11|E|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Y|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|Z|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|10|8|@$M|11|N|12|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|H|7|13|8|@]|9|@]|A|$I|J]]|$1|S|3|T|5|6|7|14|8|@$M|15|N|16|O|P]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|V|$]]

If you don't want to break the MVVM pattern and still be able to access your Map object from the ViewModel then you can expose the Map instance with a property from your ViewModel and bind to it from your View.

Your code should be structured like described here below.

The ViewModel: 

<pre><code>using Xamarin.Forms.Maps;

namespace YourApp.ViewModels
{
 public class MapViewModel
 {
 public MapViewModel()
 {
 Map = new Map();
 }

 public Map Map { get; private set; }
 }
}
</code></pre>

The View (in this example I'm using a <code>ContentPage</code> but you can use whatever you like):

<pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
&lt;ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
 xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
 x:Class="YourApp.Views.MapView"&gt;
 &lt;ContentPage.Content&gt;
 &lt;!--The map--&gt;
 &lt;ContentView Content="{Binding Map}"/&gt;
 &lt;/ContentPage.Content&gt;
&lt;/ContentPage&gt;
</code></pre>

I didn't show how, but the above code snipped can only work when the ViewModel is the <code>BindingContext</code> of your view.

I'm working on a Xamarin.Forms app using a page that displays a map.
The XAML is:

<pre><code>&lt;maps:Map x:Name="Map"&gt;
 ...
&lt;/maps:Map&gt;
</code></pre>

I know that the map can be accessed from the page's code-behind like this:

<pre><code>var position = new Position(37.79762, -122.40181);
Map.MoveToRegion(new MapSpan(position, 0.01, 0.01));
Map.Pins.Add(new Pin
{
 Label = "Xamarin",
 Position = position
});
</code></pre>

But because this code would break the app's MVVM architecture, I'd rather like to access the <code>Map</code> object from my ViewModel, not directly from the View/page - either using it directly like in the above code or by databinding to its properties.

Does anybody know a way how this can be done?

Bind to Xamarin.Forms.Maps.Map from ViewModel

Xamarin

我正在使用一个显示地图的页面来开发一个Xamarin.Forms应用程序。XAML是：<maps:Map x:Name="Map"> ...</maps:Map>我知道可以从页面的代码隐藏中访问地图，如下所示：var position = new Position(37.79762, -122.40181);Ma...

问从ViewModel绑定到Xamarin.Forms.Maps.Map
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