ApplicationBar

This sounds pretty lame and I really don’t know why Microsoft is not interested in creating an ApplicationBar that is bindable.

Property page of a WP project

You cannot predict when an app would be tombstoned in Windows Phone. But still you can simulate it by enabling a settings in the Property page of the Windows Phone project.

1. Browse to the Property page of the Windows Phone project.
2. Select the Debug tab.
3. Select the Tombstone upon deactivation while debugging.
4. Build and Run the project.
5. After the app launches, click on the Windows key to deactivate the app, there by tombstoning it.

States

In Windows Phone (WP), every app goes thru’ three different states after its instantiated.

1. Running – when the application is actually running in the foreground.
2. Dormant – when the application is deactivated, sent to background.
3. Tombstoned – when the application is terminated after living in a prolonged deactivated state.

Tombstoning referes to the process in which the application is terminated but its state is preserved by the phone. examples could be the page navigation history, UI states, etc., so that when it is resurrected, it brings back the same user experience.

Events

There are a lot of events provided by the framework for the app developers to manage these states. Here are a few of the event that takes an app across the above mentioned states.

1. Launching – raised when the application is being launched fresh from the start screen.
2. Closing – raised when the application is terminated by pressing the back  button when the application is in the foreground or when the application is tombstoned.
3. Activated – raised after launching. This event causes the app to get in to Running state.
4. Deactivated – raised before getting in to a dormant state. This event causes the app to get in to Dormant state.

State Flow (based on SDK7.1)

States of an app in WP

• When the application is in the foreground, pressing the Windows key doesn’t terminate the application. Its simple deactivates it – puts the app in dormant state.
• When the application is in the foreground, pressing the Back key terminates the application, raising the closing event.
• When the application is in the foreground, launching another task, might deactivate the app and put it in dormant state.
• When the application is in the dormant state and  if its not activated for a while or if the OS runs out of memory, then the application might be tombstoned (based on least recently used applications logic).

Difference between SDK7.0 and SDK7.1

In SDK7.0, the application is always tombstoned, meaning, there is no Dormant state. When the application is in the foreground and when the Windows key is pressed, deactivated event is raised, followed by closing event.

This is not the case with SDK7.1. When the application is in foreground and when the Windows key is pressed, application is deactivated but not tombstoned. Its simple in dormant state.

How to test

It was difficult for me to understand this initially. So I wrote two sets of application to test and understand this. One for SDK7.0 and another for SDK7.1. Its a simple app, with a toggle button (to test the state of UI) and a text block that prints the HashCode of the application itself. When I ran the 7.1 app, on pressing the Windows key and bringing it back to foreground neither changed the toggle state not changed the HashCode. When I ran the 7.0 app, on pressing the Windows key and bringing it back to foreground changed the toggle state and the HashCode.

So the conclusion is that there is no Dormant state in SDK7.0, unlike SDK7.1 and pressing Windows key simply tombstones the app.

Tombstoning

You can store your application data in to an Isolated storage when the application is tombstoned using the IsolatedStorageSettings class, which I am yet to explore and will write more when I do so.

You can find an elaborate article on the application life cycle model in MSDN.

Hope this article has given you an insight in to the application life cycle model of Windows Phones.

Windows Phone 7 - Wikipedia

As I had mentioned earlier that I am planning to start off with Windows 8 programming, I also thought it would be logical to start off with Windows Phone 7 programming. I know, Windows Phone 7 has got nothing to do with Windows 8 programming, except for the UI and thats the reason. User Experience is really important, especially for handheld devices.

Here are a few things you need  before you kick start with Windows Phone 7 programming.

• .NET and Visual Studio – you ought to be familiar with .net and Visual Studio.
• WPF (xaml to be precise) – at least the fundamentals. The book that I have linked underneath lets you learn the basics but still I suggest a book that talks just about xaml (?!?).
• **Silverlight – not necessarily; ifyou know WPF, well, thats enough.
• Visual Studio 2010 with SP1 and Windows Phone 7.1 SDK.
• Book or some kind of tutorial – obviously we start off with a book. Programming Windows Phone 7 by Charles Petzold is what I am currently learning.
• Windows Phone – even though you get an emulator with Visual Studio Windows Phone 7 SDK, the emulator is every simple and you might not find it useful if you are planing to write complex applications involving multi touch gestures, notifications, etc.

I just started off with Windows Phone 7 programming last week and is really cool. I am finding it very simple as I have been working on .NET, C# and WPF for quite some time now. If you are new to WPF, I suggest you learn it and get acclimatized to the XAML fundamentals and syntax before you start off with WP7 programming. I will also try and write about things which I find notifiable, out here.

So long, lets write some Windows Phone apps

Windows 8

Windows 8. I tried out the OS last month; pretty neat. So now, I am planning to start off with the app development.

This is where I am gonna start from. Hoping to write more soon.

1. Get a Mac. You cannot develop apps from your pc. I tried using virtual machine, but it is NOT POSSIBLE AT ALL. Forget about your pc. Go get your mac !!
2. Once you have your mac, navigate to http://developer.apple.com. You have so many resources out there which should get you on board immediately

Tips for beginners,

• Development Center – is really neat and way ahead than MSDN
• Programming Paradigm – is MVC and should be familiar if you were programming for quite a while
• IDE – XCode and InterfaceBuilder are the IDEs with which you write programs for iOS. Thou’ they are not as good as Visual Studio, they are pretty good for beginners
• Programming Language – ObjectiveC – so far is the biggest challenge for me. If you are new to this, you will find it to be really weird
• Unmanaged Code – if you are a .net programmer with no experience writing C/C++ programs, you should be extra careful in here
• Tutorials and Samples – development center has got everything for you. Do not worry about this

Overall, the experience is good and exciting so far.

UserControl is a composite control. We use UserControl when you want to group similar controls and reuse them across multiple windows/pages. UserControl is not considered as a single control by the logical tree. i.e., if the UserControl contains three buttons and a list box and when this UserControl is used in window, the logical tree of the window can identify each of there controls (buttons and list box).

CustomControl is a single control with a control template located in the “Themes->Generic.xaml” file. When CustomControls are used in a window/page, the logical tree cannot identify its internals. For example, if you want to use snip control (a control that has up and down buttons to scroll values in a textbox), then create a custom control that inherit from Control class and give it a theme (default ControlTenplate).

Okay, now when to use what ??

If you are writing a CustomControl, its template can always be overridden. Which means, if you want to ship a control as a library and if you want it to be customizable by others, then go for CustomControl. Otherwise, its simple, go ahead and use a UserControl

Hope you got the difference now.

One more happy news, they even have a WPF designer is a quite awesome. Give it a try

1. Place a grid as the base panel (don’t add any Background property to it)
2. Add an ellipse and a content presenter to this
3. Add a Click event handler to the button
4. Run it and try to click on the white space, the event will not be raised !!!

Go back to the template,

1. Add a Background property to the grid and set the value to Blue (can be any color other than transparent)
2. Run it and try to click on the Blue color, the event will be raised !!!

Go back to the template,

1. Set the value of the Background Property to Transparent
2. Run it and try to click on the white space, the event will still be raised !!! (WHY ?!?)

Looks weird to me thou’