XAML Xamarin OnPlatform Binding - xaml

Question

I think my code is self explanatory:
<Label Style="{DynamicResource labelStyle}"
HorizontalTextAlignment="End" Text="{Binding message}">
<OnPlatform x:TypeArguments="Color">
<OnPlatform.iOS>
{DynamicResource rightBubbleFontColor}
</OnPlatform.iOS>
<OnPlatform.Android>
{DynamicResource rightBubbleFontColor}
</OnPlatform.Android>
<OnPlatform.Android>
{StaticResource rightBubbleFontColor}
</OnPlatform.Android>
</OnPlatform>
</Label>
I'm trying to dynamically bind a color to the label. Depending on the current platform, it has to be another type of resource (DynamicResource or StaticResource).
I get this exception when trying to build the solution:
System.ArgumentException: An item with the same key has already been added.
UPDATE
I now have this code:
<Label Style="{DynamicResource labelStyle}"
HorizontalTextAlignment="End" Text="{Binding message}">
<Label.TextColor>
<OnPlatform
x:Key="RightBubbleFontColor"
x:TypeArguments="Color"
iOS="{DynamicResource rightBubbleFontColor}"
Android="{DynamicResource rightBubbleFontColor}"
WinPhone="{StaticResource rightBubbleFontColor}">
</OnPlatform>
</Label.TextColor>
</Label>
And I get the following error message:
Object reference not set to an instance of an object.
When I replace the binding to a color it works.
Working example:
<Label Style="{DynamicResource labelStyle}"
HorizontalTextAlignment="End" Text="{Binding message}">
<Label.TextColor>
<OnPlatform
x:Key="RightBubbleFontColor"
x:TypeArguments="Color"
iOS="Red"
Android="Green"
WinPhone="Blue">
</OnPlatform>
</Label.TextColor>
</Label>
So it has to be an issue with the way I'm trying to bind this I guess.
EDIT
Asked a new question to describe the problem better: https://stackoverflow.com/questions/39852888/xamarin-forms-use-dynamicresource-or-staticresource-depending-on-os

Answer 1

You have two <OnPlatform.Android> elements. I'm assuming the last would be <OnPlatform.WinPhone>.
EDITED
Now that you have that fixed, maybe try this for it to actually work?
<OnPlatform
x:Key="BubbleTextColor"
x:TypedArguments="Color"
iOS="{DynamicResource rightBubbleFontColor}"
Android="{DynamicResource rightBubbleFontColor}"
WinPhone="{StaticResource rightBubbleFontColor}" />
Then bind it where necessary.
Not sure if it will work any differently than what you already have, but I guess it's worth a shot.