Dynamic application title on Windows Phone 7.x using recources

I was developing a stupidly simple application for personal use and came up with a humorous idea. I wanted the application title on top of the app pages to also show the version. However I didn’t want to add code to every code-behind file to make it so. I came up with the idea of adding the string, used as the application title, to the application resources. Then I used a simple binding to make it all happen.

<!-- In App.xaml -->  
<Application.Resources>  
    <sys:String x:Key="ApplicationTitle">FUEL CONSUMPTION - v1.0</sys:String>  
</Application.Resources>  
<!-- In MainPage.xaml -->  
<StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">  
    <TextBlock x:Name="ApplicationTitle" Text="{StaticResource ApplicationTitle}" Style="{StaticResource PhoneTextNormalStyle}"/>  
</StackPanel>

This worked excellently, but; I didn’t want to add the version to the resources everytime i updated the application. Of course this is a bit lazy since it’s not that much of a hassle, but there’s something a bit more cool about it updating by itself.

To make this dynamic I needed to do some coding in C#: To get the version number of the application i fetched the version number of the assembly. The version number of the assembly is set by right clicking the project in Visual Studio and click Properties. From there you click on Assembly Information and edit the version numbering there. The resources are represented by a ResourceDictionary and I tried this approach:

// In MainPage.xaml#PhoneApplicationPage_Loaded event handler

// Get the version number from the assembly
var nameHelper = new System.Reflection.AssemblyName(System.Reflection.Assembly.GetExecutingAssembly().FullName);

// Set the new string as the resource string
Application.Current.Resources["ApplicationTitle"] = string.Format("FUEL CONSUMPTION - v{0}.{1}", nameHelper.Version.Major.ToString(), nameHelper.Version.Minor.ToString()));

This didn’t work to well though. Every time I tried doing this, a NotImplementedException was thrown at me. After some googling around it turned out that the setter for entries in the ResourceDictionary only does this one thing; throw an NotImplementedException. I went onto the big, wide interwebs and asked on Stack Overflow if anyone knew an answer. After some tips from some brilliant minds, I got inspired and came up with a solution.

Adding new resources to the application isn’t a problem, nor is removing them. All I had to do was to remove the resource with the key “ApplicationTitle” and add it again with the new string.

// In MainPage.xaml#PhoneApplicationPage_Loaded event handler

// Get the version number from the assembly
var nameHelper = new System.Reflection.AssemblyName(System.Reflection.Assembly.GetExecutingAssembly().FullName);

// Check whether the resource is present and then delete it
if(Application.Current.Resources.Contains("ApplicationTitle"))
 Application.Current.Resources.Remove("ApplicationTitle");

// Add the resource again with the updated string
Application.Current.Resources.Add("ApplicationTitle", string.Format("FUEL CONSUMPTION - v{0}.{1}", nameHelper.Version.Major.ToString(), nameHelper.Version.Minor.ToString()));

This didn’t yield the right result either. It did work if I navigated to another page in the application. As it turns out, you see; the resources are not dependency properties, which means they don’t send an event for changes made in the object. That’s why the application title does not update in MainPage.xaml. This is however easily remedied by putting the previous code into the Application_Launching event handler which launches before the PhoneApplicationPage is even called, as per the Windows Phone execution model.

That’s how I finally managed to get a “dynamic” application title without having to add code to every PhoneApplicationPage I make, I only have to bind the title of the page to the application resource.

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