I built an app just for myself recently and decided to share it.  Those are always the best apps to build, ones that have some personal meaning or use for yourself.  And this one is no exception.

You can download this app from the Windows Phone Marketplace – Mariners News.

2 hours – ready, set, go

I attended a class where we had just two hours to make a start to finish app.  I actually didn’t intend to build this app, and had no idea we were going to do this at the event.  I am actually quite glad we did, as it showed me I could do a lot more in a phone app in just a few hours than I would have thought possible.

Request Data from Bing

The previous topic of the class had been using the Bing API to make requests for data and news stories.  Just that morning I had been looking for a way to get news about the Seattle Mariners.  There was one app in the marketplace, but the UI was terrible and slow.  Viola, an idea is born.

Version 1.0 total time spent 3:15

Ok, I did make the app in under two hours, but I spent an additional hour and fifteen minutes at home that night making the icons, testing for the marketplace certification, putting in the Ad control, and preparing the submission.

Trademarked material

Oops, I grabbed the official MLB logo when I built the icons.  I wasn’t really thinking about it the night I submitted, I just went to MLB.com and grabbed the official logo.  Almost the next day the Windows Phone Developer Blog came out with an article about avoiding trademark trouble. 

I should have known better.  Really, I have done this type of thing before.

Designing my own logo

So I sat down that evening using Expression Design and built a new logo.  It is close enough for people to recognize it as the logo, but it is my version of it.  No trademark or copyright issues!

Quick, simple and clean.  I like it.

Waiting on certification

And then I began the long wait for certification (which you can’t cancel or abort).  So I thought what else would I want to change?  I am going to need to submit an update anyway, better make it worth it.

Navigation and other changes

At this point I thought more about the navigation experience.

I didn’t like the display of the news articles and with about two evenings of playing I came up with the following design that I am much happier about.

Notice the stories are cut at two lines, if you click you get the complete RSS or news story as it was returned from Bing.  Then if you want you can launch out to IE from that more detailed page. 

I got rid of the images for the source (too much space), and just added an tagline, then about how long ago it was posted.  Seeing the date and time doesn’t really do much for you, but seeing about four hours ago seems to give it a fresher feeling.

Links and Social pivots

This is where I started thinking about what else I would do with a Windows Phone.  I want to check for tickets, directions to SafeCo, tweet about the game, etc.

Most of these are pretty simple stuff, but add a lot of usage to the app. 

Uniquely Mobile

The call for tickets actually goes call the correct Ticketmaster line for you.  I don’t know of any other sports app that does that, and it is a uniquely mobile experience.  You wouldn’t want that on your desktop, but on my phone it makes perfect sense.

Directions to SafeCo Field.  Another unique experience for mobile phones.  I may be lost downtown while going to a game (it happens).  Quick couple of taps and I am getting directions.

Get on demand updates of news and scores through SMS is a feature that ESPN offers.  But I can never remember the number, so I built it in.  Now with a quick tap I get the latest box scores or news.

Share the #mariners spirit is something I want to add more to over time.  The ability to profess the love for your team, taunt the opponent, or just complain about the call are all social elements to the game today.  I would like to build in more Twitter integration to let users interact about the game while watching a game.

Version 2 was ready before Version 1 was live

I actually finished this version of the app just a few hours after the version 1 was approved for the store. But even after approval it still takes 24-48 hours before an app goes live on the site.

I was very happy to be able to submit a quality update almost immediately.  Now I just have to wait for it to be approved! 

Better Live Tile

This was a really fun project, and one that I am sure I will continue to update as I find more things I want in it myself.

I am already thinking about a way to use a live tile to show me the next team opponent and the time of the that game.  Too bad you can’t add calendar items on WP7, maybe a push notification that the game is getting ready to start?  Hmm.  I can listen using MLB At Bat to every game, so that might work.  Ahh the possibilities.

Enjoy your projects, and hopefully from baseball this year too!

The interview I did for Channel 9 Inside Windows Phone is now up!

Channel 9 MSDN Link

Embedded Video

My thanks to Larry for having me on the show to talk about CRUD. People seem to think that with mobile apps the basic concepts of CRUD have gone away, but that is not true! You still need to think through the basic data operations the same as almost any other application.

Here is the post for the original XAPFest talk.

XAPFest talk Managing Data on Windows Phone 7

I did an after hours XAPFest talk a while back on Managing Data on Windows Phone 7 that is now published on the Microsoft Research site!  I am actually sort of proud that this session was the #2 most attended talk at XAPFest!

Microsoft Research – Managing Data on Windows Phone 7

I did a follow up blog post entitled Minimal virtualized data list for WP7 showing how to implement the code I spoke about in the video.  The source for that is available on Bitbucket.

I recently gave a talk about data management on Windows Phone 7 for XapFest and I put in a slide about virtualizing your data for data bound objects.  I didn’t really think it was that big of a topic when I was putting together the talk, but it generated a lot of interest from attendees. 

I am going to demonstrate the minimal virtualized data collection object you can easily create for data binding with a Listbox. 

For this example I am using a simple class named FeedItemDataModel.  This represents a class that holds a single item from an RSS Feed.  In this simple implementation the values are simple and set in the constructor.

The sample application shows a UI with a collection of this object databound to the UI and lets you jump to a specific index in the list.  The red text you see is a memory watcher class that shows memory usage within your app.

More...

I got an email from someone today asking about how to take a resource from their XAP (which is read only), and put it in a location where they can update the file. 

Initial Data Load

I highly recommend this approach for getting an initial data load for your application.  Give the application a base of files to work with rather than requiring an initial round trip to a server for those files.  It is fine to need to update them almost immediately.  Think about the scenario where the user has no network access (a first run of the app this is really vital).  Does the user get an error that no data is available, or do they get a nice default experience?  Even if you just put in data that says “no data here yet”, that is better than a blank screen to the user.

Create File From Resource

I put this in a utilities class as a static method since it doesn’t really need any state.  One thing to ensure you do is put a using() block around the objects that are disposable.  This ensures they are cleaned up and released as quickly as possible.  I think this is a common reason why people think they need to GC.Collect, they are not cleaning up memory.

public class FileUtilities
{
/// <summary>
/// Given a resource name, create a file in the isolated storage.
/// Resources are read only, but copying them to the isolated store means you can edit them.
/// Useful for including a starter file in your XAP, and then copying it out to storage
/// for editing it at runtime.
/// </summary>
/// <param name="resourceName">The name of the resource</param>
/// <param name="fileName">Optional param for the name of the file, 
///       by default uses the same name as the resource</param>
public static void CreateFileFromResource(string resourceName, string fileName = null)
{
    // Find the resource and get the stream
    // Note the using() block to ensure this gets cleaned up when we are done
    using (var resourceStream = Application.GetResourceStream(
                                  new Uri(resourceName, UriKind.Relative)).Stream)
    {
        // Get the location where we can write files
        using (var userStorage = IsolatedStorageFile.GetUserStoreForApplication())
        {
            // Use the filename (if given) or the resource name
            using (var newFile = userStorage.CreateFile(fileName ?? resourceName))
            {
                byte[] byteBuffer = new byte[4096];
                int bytesRead = -1;
                while ((bytesRead = resourceStream.Read(
                                     byteBuffer, 0, byteBuffer.Length)) > 0)
                {
                    newFile.Write(byteBuffer, 0, bytesRead);
                }
            }
        }
    }
}}

Please forgive the formatting above, trying to make it fit on a smaller size screen.

On a Windows Phone 7 project I am currently building I had a need to build a factory that instantiates different concrete classes depending upon an object at runtime.   I have a number of information feeds, that all have different classes built to actually go get their data.  One for RSS Feeds, one for Twitter, etc.  Each Feed has a property for the FeedType, this is the information needed to determine what class to instantiate at runtime.

I have written this pattern many times, but I ran across an interesting post on StackOverflow where Steven gave a different approach to solving this without the classic giant switch statement in the Create method.   I thought it was neat enough to use in my application and share here.

There are a couple of steps you have to take, but none of them are difficult.

• Decorate your objects with a custom attribute
• Build the object types using reflection
• Implement your factory method

Custom Attribute

The attribute I added is called FeedTypeAttribute, I then add it to the concrete feed processor classes.

class FeedTypeAttribute : Attribute
{
    private int _feedType;

    public FeedTypeAttribute(int feedType)
    {
        _feedType = feedType;
    }

    public int FeedTypeId
    {
        get
        {
            return _feedType;
        }
    }
}

[FeedTypeAttribute(1)]
public class StaticFeedProcessor : IFeedProcessor
{
    public StaticFeedProcessor()
    {

    }

    public void ProcessFeedModel(FeedModel feedModel)
    {
        throw new NotImplementedException();
    }
}

Factory Method Using Custom Attributes

public class FeedProcessorFactory : IFeedProcessorFactory
{
    private static Dictionary<int, Type> processorList = new Dictionary<int, Type>();

    static FeedProcessorFactory()
    {
        // Get the types in this assembly that implement our custom attribute
        var targetTypes = from type in Assembly.GetExecutingAssembly().GetTypes() 
                         where type.CanBeTreatedAsType(typeof(IFeedProcessor))
                         where !type.IsAbstract && !type.IsInterface
                         let customAttributes = type.GetCustomAttributes( typeof(FeedTypeAttribute), false)
                         let attribute = customAttributes[0] as FeedTypeAttribute
                         select new { type, attribute.FeedTypeId };

        processorList = targetTypes.ToDictionary(p => p.FeedTypeId, p => p.type);
    }

    public IFeedProcessor CreateProcessorByFeedType(int feedId)
    {
        Type feedType = processorList[feedId];

        return Activator.CreateInstance(feedType) as IFeedProcessor;
    }
}

The key here is the type.GetCustomAttributes() call.  The linq expression gets all the type of the current assembly where the type can be assigned from the IFeedProcessor class.  We have to ensure the class is not abstract or an interface, and then get the custom attributes. 

The let clause in the linq expression can be thought of like a local temporary variable.  Assigning the attributes to it, and then processing them in the final select.

Consuming the Factory

Consuming the factory is then as simple as instantiating a factory object and calling the CreateProcessorByFeedType function.  A fully allocated processor is returned ready to handle the feed.

// This is in my container object
private static IFeedProcessorFactory _feedProcessorFactory = new FeedProcessorFactory();


// This is in the function to process the feeds
IFeedProcessor processor = _feedProcessorFactory.CreateProcessorByFeedType(feed.FeedType);
processor.ProcessFeedModel(feed);

Less Coupling is Good

I have run into this a few times and always have to go to the MSDN to find the answer.  I have a situation where I needed to determine if a given type can be treated as a base type in an object factory.  I wanted to be able to create my concrete classes without having to do a switch statement for each type.

First I had to determine if the types were assignable to each other, then find the type to implement.  I will cover that in another article.  In this one I just want to cover the assignment test.

Can this type be assigned?

There is a function IsAssignableFrom that you can call on a System.Type. 

if( ParentType is ChildType )

It actually has to be written the other way around.

if( ChildType.IsAssignableFrom(ParentType) )

Quick Extension Method

So instead of having to do that all over my code, I wrote an extension method to allow me to do it following a different ordering.  I actually got this basic idea from one of the comments on the MSDN page.

if( parentType.CanBeTreatedAsType(childType) )

As you can see the extension method lets you write the syntax in a more natural manner.  Your preference may differ, but this makes more sense to me.

Example Code

public static class DataExtensionMethods
{
        public static bool CanBeTreatedAsType(this Type CurrentType, Type TypeToCompareWith)
        {
            if (CurrentType == null || TypeToCompareWith == null)
                return false;

            return TypeToCompareWith.IsAssignableFrom(CurrentType);
        }
}

void Main()
{
    System.Type parentType = typeof(ParentClass);
    System.Type childType = typeof(ChildClass);
    
    bool ChildToParent = childType.CanBeTreatedAsType(parentType);
    Console.WriteLine("Child can be treated as parent: " + ChildToParent );
     
    bool ParentAsChild = parentType.CanBeTreatedAsType(childType);
    Console.WriteLine("Parent can be treated as child: " + ParentAsChild );
}

public class ParentClass
{
    public ParentClass()
    {
    }
}

public class ChildClass : ParentClass
{
    public ChildClass() : base()
    {
    
    }
}

This is another of those posts for my future self, because I know I won’t remember this little tip.

Set startup through app manifest

The WMAppManifest.xml has a property that tells it where to send the default launch of the application.

    <Tasks>
      <DefaultTask Name="_default" NavigationPage="MainPage.xaml" />
    </Tasks>

So the normal launch page is MainPage.xaml. But you can change it to another page, and include your parameters just like from a secondary tile!

    <Tasks>
      <DefaultTask Name="_default" NavigationPage="/TileDetails.xaml?myid=2" />
    </Tasks>

Now you can just press F5 and debug just as if that secondary tile had been clicked.

If you have not looked at the toolkit before you seriously owe it to yourself, go get it now!

Coding 4 Fun Phone Toolkit

Windows Phone Geek has also done a great intro post on one of the new controls (the MetroFlow control).  Getting started with MetroFlow Control is a great read, even just to get up to speed with the overall concepts of the toolkit.

I have been adding animations to a Windows Phone 7 app that has a panorama control and ran into a problem I have seen others post online.  I figured it out, so I thought I would take a minute to explain how.

Get ready to add transitions

The Silverlight Toolkit is the way you want to go about adding quick and easy animations when a page loads and navigates away from the current page.

If you are not familiar with the basics visit the link above, or read this really good tutorial about wp7 page transitions on Windows Phone Geek.

The basics are that you have to include the toolkit, and you have to modify the root frame of your application to be a transition page instead of a normal phone page.

In a typical application you have the RootFrame declared in your App.xaml.cs like this:

    public partial class App : Application
    {
        /// <summary>
        /// Provides easy access to the root frame of the Phone Application.
        /// </summary>
        /// <returns>The root frame of the Phone Application.</returns>
        public PhoneApplicationFrame RootFrame { get; private set; }
    }

But for transitions to happen you need to change the object to a TransitionFrame when your InitializePhoneApplication is called.

            // REPLACE THE FIRST LINE WITH THE SECOND
            // RootFrame = new PhoneApplicationFrame();
            RootFrame = new TransitionFrame();

This will give you the ability to add transitions to your page.

I prefer to define my transition style at the application level, rather than the page level.  Usually I want all the pages to behave the same, so this gives a nice central point for all of them to reference it.

More...