Blog

Lesson learned on app error reports

Wed, 25 Jan 2012 06:33:17 GMT

I've been struggling with an error in one of my Windows Phone apps. I finally was certain that I had fixed it but yet I continued to get error reports labeled with the newest version number (I include that in the subject of the error email). I even released a second update to fix it and still got reports! I finally figured it out though. My app writes out the stack trace to isolated storage when there is an uncaught exception (you can't send an email while the app is going down...). On next launch, the app prompts the user to email the stack trace. The problem is that if the crash occurs on one version, then they upgrade, the trace will reflect the newest version -- the one without the bug! I'll need to add the version of the app at the time the crash occurred, so if a newer version emails it I can tell! Kind of bone-headed I guess, but it took me way too long to figure it out. If you implement exception reporting like this, keep it in mind! Of course, you can just use the exception reporting on the Create hub, but it's nice this way since the user gets to have some control, and you get immediate notification.

Metro Lockscreen Creator update

Fri, 20 Jan 2012 08:44:11 GMT

I want to apologize to all of the users of my Metro Lockscreen Creator app on Windows Phone. My last updates have caused problems for users of previous versions. This is a scenario that I haven't been testing, and unfortunately the Marketplace certification process doesn't take it into account either. If the app is immediately crashing for you, please remove and add it again from Marketplace. I just submitted a bug fix that should go live in a few days. I added some highly requested features in the new updates, but the problems have prevented people from being able to see them. I hope this helps. Thanks for your support, and some very kind reviews (in between the justifiably angry ones!).

Expression Blend Crashes on Every Single Startup

Sun, 15 Jan 2012 08:21:01 GMT

Have you been having trouble with Blend 4 crashing every time you start it up? I was, until I discovered the "easy" fix. It turns out that this happens if you install the Visual Studio 11 Developer Preview. There's a bug that they fixed right after releasing it! This is the price to pay for installing beta software alongside production software. For now, copy the following lines to a batch file and run it.

%windir%\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "%ProgramFiles(x86)%\Microsoft Expression\Blend 4\Microsoft.Expression.Framework.dll"

%windir%\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "%ProgramFiles(x86)%\Microsoft Expression\Blend 4\Microsoft.Expression.Blend.dll"

%windir%\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "%ProgramFiles(x86)%\Microsoft Expression\Blend 4\Microsoft.Expression.Project.dll"

%windir%\Microsoft.NET\Framework\v4.0.30319\ngen uninstall "%ProgramFiles(x86)%\Microsoft Expression\Blend 4\Microsoft.Expression.WindowsPhone.dll"

Source: Microsoft Connect - Blend 4 Crashes on Startup

"Failed to connect to device as it is developer locked" error

Mon, 09 Jan 2012 03:26:15 GMT

I started getting this error message on a phone that I’ve had unlocked for some time. My App Hub membership is up to date, and the Windows Phone Developer Registration tool was returning “Registered” each time. After digging around in App Hub, I saw that under devices my phone was listed with an Expiration Date of a few days ago. Apparently, my first registration of the phone on 1/3/2011 expired a few days ago. I actually had to click Remove there, and run the developer registration utility again. Now it works great! Refreshing the devices page, I now see a current registration date with a future Expiration Date. Hopefully Microsoft can get this messaging improved in the future.

Fixing that darn AdControl when it won't show up

Mon, 09 Jan 2012 03:25:49 GMT

I’ve had two apps recently that I ended up submitting with a problem. In both cases I had the AdControl, but no ads were showing (the control would appear for a second, then collapse). I made the mistake of assuming that this was a temporary problem and I just published them without waiting to see it work. It never did end up working though.

After way too much digging without finding anything, I decided to turn on all thrown exceptions while debugging.

Click the Debug | Exceptions menu command

For at least Common Language Runtime Exceptions, check Thrown

What a difference! With all thrown exceptions popping up, I could immediately see that I was missing two capabilities in the WMAppManifest.xml file (ID_CAP_WEBBROWSERCOMPONENT and ID_CAP_PHONEDIALER). Such a simple fix! Expand your Properties node in the project, then open the file and add both of them to the Capabilities element:

I really wish Microsoft would add capabilities to the UI in Project Properties. It would also be nice if these were added automatically somehow when the AdControl was included. Hopefully this will help to prevent someone else from banging their head against the wall!

Tasks in Visual Studio

Sun, 04 Dec 2011 23:35:05 GMT

Are you using tasks in Visual Studio? You should be! It can be difficult to keep track of things that you need to finish. Whether it’s hacks that need to be cleaned up, or code that’s unfinished, there are many spots that you might need to return to. Tasks are how you can track of these. On any line of code, create a comment starting with “TODO” and followed by the task that you need to complete:

This automatically becomes a task that can be managed across the solution. In order to see all such lines, go to the View menu and click Task List. Now you can sort by file, line number, or alphabetically by task.

You can also click the Comments drop-down list and then click User Tasks to create tasks that aren’t associated with specific lines of code.

There are settings available so you can create other tasks too. In addition to TODO, you can specify HACK or create your own. To to Options | Environment | Task List, and you can manage the prefixes and what priority they have:

Give tasks a try. Chances are, even if you weren’t aware of this, you were likely using code comments to indicate work to be done. Use this simple convention, and keep track of them in a more organized fashion!

Windows Phone Game Contest

Fri, 02 Dec 2011 20:44:00 GMT

Like gaming? Like making games? Now you can step up your game with a new Dell Alienware M18x gaming laptop or an Xbox LIVE Gold card just for submitting your super cool Windows Phone game to the Marketplace. It’s easy – just go here to find out how you could win some pretty sweet prizes.

For event code, enter “AKULP” and get those entries in! You have until 2/29/2012 to enter.

Link: http://on.fb.me/WPgameApp

Great contests for Windows Phone apps!

Tue, 29 Nov 2011 07:37:36 GMT

Are you working on Windows Phone apps? If you’ve been working on something, now’s the time to get it published! Any app published between 10/15 and 12/31 can get you an entry for a Samsung Series 7 Slate (like at PDC)!

Every five apps gets you an entry for free advertising for the app of your choice. If you need help (within reason!), I’d be glad to provide some guidance. Once the app is published, use the below link to enter the app’s GUID as an entry. For promo code, use “AKULP”.

Link: http://www.windowsphone7event.com/GoMango/

Custom mime types with Cassini

Tue, 22 Nov 2011 17:43:08 GMT

After too much time trying to get some video files to play using the video tag, I did some searching and learned that the ASP.NET development web server (Cassini) doesn’t support custom MIME types. Even after adding the mimeMap entries in the web.config file properly, it just ignores those elements. The simple solution is to do what I should have anyway: set the project to use IIS Express.

Something interesting that I learned is that Chrome doesn’t actually seem to care about the MIME types. IE and Firefox refused to load the videos, but Chrome was fine with it. I had the type attribute set in the source elements, so Chrome was happy, but IE and Firefox apparently require the server MIME type to match. So much time wasted on something that should have been so easy!

Clever move, Firefox!

Fri, 18 Nov 2011 21:38:59 GMT

I used to be a die-hard Firefox junkie. Back when IE was in versions 7 and 8, IE just wasn’t a good choice for working on standards-compliant web sites, and as new HTML features started rolling out and IE didn’t keep up, I left it behind. In the last year or so, I upgraded to Chrome, and then IE 9 when it came out. Both did an excellent job with standards (though IE’s release cycle means it’s behind again until IE 10) and were nice and fast. I just reinstalled Firefox to do some cross-browser testing, and I’m impressed by one specific feature: the venerable JavaScript alert(). Both IE and Chrome have the ridiculous method of using the system message box for the JS alert. This has the effect of creating a modal window for one out of many potential tabs -- inexcusable. It turns out that Firefox has made a great choice by creating an in-browser dialog, thus having no effect on the overall window or other tabs. This is a wonderful addition! Also, since it is clearly part of the web page, there is no longer the worrisome factor of naïve users believing it to be a system message. Kudos, Firefox!

Great tool for SQL Server Compact Databases

Thu, 17 Nov 2011 18:25:26 GMT

How do I examine the contents of a SQL Server Compact database? How do I open an sdf file in SQL Server Management Studio? If you’ve wondered about this, then you need to get the SQL Server Compact Query Analyzer tool by Christian Helle. This tool lets you just double-click the sdf file to open it in a query analyzer window where you can examine the schema and easily view the data. I am in love with this tool lately! I can easily open my Windows Phone or desktop SQL Server Compact databases and see exactly what got stored rather than writing more code anytime sometime doesn’t look right. This is quick and it works great! Even better, it’s open source and available on Codeplex!

Link: http://sqlcequery.codeplex.com

Cool interactions with Kinect

Tue, 15 Nov 2011 07:33:44 GMT

I like the idea of gestures for manipulating workspaces, but it’s difficult to get it right. Code Spaces is a Microsoft concept for developer code sharing using Kinects, Windows Phone devices, and touch-enabled laptops to collaborate in group settings. It makes use of Code Bubbles, which I mentioned last year. The modern code editor view works well enough for editing, but isn’t suited for presentations or collaboration. It’s fun to see potential future directions.

Source: http://www.engadget.com/2011/11/14/microsoft-outlines-code-space-looks-to-include-kinect-in-confer/

DataContract serialization on Windows Phone

Tue, 04 Oct 2011 16:53:55 GMT

I wasted many hours on a problem with serializing data on a Windows Phone app. I’m using DataContract/DataMember. I learned many things along the way, but it was still way too much time spent. For example, I learned that I don’t need to always use DataMember as I do. If you don’t use attributes, all public properties will be serialized. If you use DataMember anywhere, then it switches to opt-in. Alternatively, you can use IgnoreDataMember to opt-out on specific public properties.

I read that ObservableCollection isn’t serializable. Thinking that to be true (still not positive on this one), I wrote serializer methods (with the assistance of the OnDeserializing/OnDeserialized/OnSerializing/OnSerialized attributes). I hadn’t been aware of these, but they really help when you need finer control over the process. In my case, I serialized using an array, then when deserialized, I copied the array items to the ObservableCollection.

In the end though, I kept getting errors about my class not being public, and therefore failing to deserialize (serializing worked fine). I couldn’t figure it out.

I wrote a method like this:

[OnSerializing]
void OnSerializing(StreamingContext ctx)
{
}

The examples that I found indicated that this would be fine, so I assumed that the issue was elsewhere. After hours of troubleshooting, I realized that all I needed to do was make those methods public! I don’t like that. Those methods shouldn’t be public. It’s to do with the medium trust environment of WP7. In other environments, you can do what I did above just fine, but the serializer won’t have access to the methods without public access. I hope that I’m wrong and that there’s a different way to do this, but it seems like the only way.

Mouse Without Borders

Tue, 13 Sep 2011 22:33:58 GMT

Certainly not the first such product, but this tool Microsoft lets you share keyboard and mouse between computers on a network. I’ve never been able to get Synergy to work, so even with its cross-platform promise, it doesn’t matter! Mouse Without Borders even lets you drag and drop files, share the clipboard, and login/logoff across all systems. This is a great solution for those times that you have a laptop next to your desktop and you keep looking at the wrong screen while you’re typing! It’s free which is nice. I like that it comes out of Microsoft Garage though. This is like Google’s 20%, except Microsofties have to do it on their own time. They get a great lab though and internal support. Sounds like a pretty nice setup!

Source: http://www.engadget.com/2011/09/12/microsofts-mouse-without-borders-the-kvm-that-killed-the-kvm/

Error with Ad Control: Invalid format being parsed

Wed, 07 Sep 2011 00:52:27 GMT

I’m using the Microsoft Advertising control and had made some layout changes in the XAML. All of a sudden I started getting the very unhelpful message “Invalid format being parsed: <”. Everything looked fine, and it was certainly valid XML/XAML. I finally discovered that the control *requires* the use of both Width and Height being explicit set. The Grid containing it provided layout width and height and it looked fine in the preview window. As soon as I added those properties though, all was fine! Sounds like a bug (and I’m sure if I checked Connect I’d see it there).

Good deal on a Windows Phone

Mon, 22 Aug 2011 15:54:08 GMT

The HTC 7 Trophy is on sale at Buy.com right now for just $269, no shipping, and unlocked! If you are looking for a Windows Phone, this is a great deal to avoid contracts.

Tip: Do not dispose objects multiple times

Fri, 12 Aug 2011 22:37:25 GMT

Another new thing I learned! I’m a big fan of using statements. I put them in whenever I can to simplify things. If you don’t use them, you should. Any object that implements IDisposable requires that you call Dispose() on it when finished with it. In the past, the best way to do this which was resilient to errors (what if an exception occurs and you miss the call to it?) was to add a try/finally block. Even if you didn’t catch anything, you’d be guaranteed that the finally would execute. In there you would check for null and dispose of the object. With a using block, the dispose call happens as soon as scope ends. It’s perfect!

Running static code analysis from Visual Studio (FxCop), I learned of a potential problem when I got the odd error: “Do not dispose object multiple times.” Puzzling. No where do I do that. Look at this block:

using(var reader = new BlahReader(param))
{
    using( var thing = new BlahThing(reader))
    {
        // Do something
    }
}

Everything looks good... or so I thought! I didn’t realize that the inner dispose would also dispose of the outer object if it wraps it. Perhaps specific to IO-based object..? By doing it this way, the “reader” object will be implicitly disposed by the “thing” using block. Then, the outer block goes out of scope and it gets disposed of again. Most objects check for that and won’t complain, but it’s not something you should count on. The recommended (and ugly) alternative is like this:

var reader = new BlahReader(param);
try
{
    using( var thing = new BlahThing(reader))
    {
        reader = null;
        // Do something
    }
finally
{
    if( reader != null ) reader.Dispose();
}

If the “thing” initializer throws an exception, the “finally” block will dispose of “reader.” If all goes well, then the single “using” block will dispose of both. Not as nice, but I suppose it’s a good idea!

Link: http://msdn.microsoft.com/query/dev10.query?appId=Dev10IDEF1&l=EN-US&k=k(%22DO+NOT+DISPOSE+OBJECTS+MULTIPLE+TIMES%22);k(TargetFrameworkMoniker-%22SILVERLIGHT%2cVERSION%3dV4.0%22)&rd=true

Tip: Access to modified variable in closures

Thu, 11 Aug 2011 22:57:05 GMT

I learned a simple trick today. If you use closures (lambdas) in LINQ queries or other such contexts, you automatically capture all variables and their values from the outer scope. You may not be aware of this, and you may never use it, but it allows you to do things like this:

string val = “blah”;
var items = Items.Where(i=>i.Name == val).FirstOrDefault();

Very handy. On the other hand, in order for this to work you can’t use variables that will change, since you aren’t guaranteed of the order of execution in all cases. This is especially true in loops:

for(int x = 0; x < 10; x++)
    itemsCount += Items.Where(i=>i.Value == x).Count();

I know, dumb example, but the risk is that since x changes, you’ll likely get a warning about “access to modified variable in closure.” The simple fix for this is to create a closer-scoped variable to copy the value. In this (overly-)simple example, all you need to do is this:

for(int x = 0; x < 10; x++)
{
    int xcopy = x;
    itemsCount += Items.Where(i=>i.Value == xcopy).Count();
}

Note that in this example, you are probably safe, since Count() forces the LINQ query to execute immediately, but the general fix is still a good one to remember.

Interesting package!

Fri, 05 Aug 2011 20:08:10 GMT

I order from China/Hong Kong fairly often since it can be difficult to source certain parts, at least for any reasonable amount of money. My latest purchase (TRRS cable, male on both ends) just arrived today. I’ll be blogging about why later. In the meantime, I thought I’d show what a one Jiao note looks like. Makes the purchase an even cheaper one (by a penny or two)!

Coding4Fun: Where’s My Car?

Thu, 04 Aug 2011 21:58:30 GMT

I’ve had an app in the Windows Phone Marketplace for a few months now. It helps you find where you parked your car by mapping, routing, and a photo of the spot. Today, I published an article talking more about it, and highlighting that the full source code is available on CodePlex. Enjoy!

Link: http://channel9.msdn.com/coding4fun/articles/Wheres-My-Car