Pass data from User Control to Parent page in Windows Phone 8.1

While using User Controls in Windows Phone, we often get into a situation where we need to pass some kind of data from the user control to the parent page, when any operation is performed on the user control. Delegates can be used to pass data from the User Control to the Parent page. We reference C# Corner’s article to apply the same logic in Windows Phone 8.1

Step 1: Create a User Control

Firstly, we create an User Control with a button in it.

Step 2: Declare a delegate on the User Control

Create a delegate on the user control, that can encapsulate a method that takes no input and returns a DateTime type.

Step 3: Create an event on the User Control

Declare an event on the user control, that is of the delegate type that we created.

Step 4: Using User Control in the Parent Page

Next, we use the User Control in our MainPage.xaml.

Step 5: Subscribe to the User Control event in the Parent Page

Our main page will subscribe to the event that we created on the user control, to get notification of when the event is fired on the user control.

Step 6: Execute the Event Explicitly in the User Control

Next, when the button click functionality is done, we explicitly execute the event by calling the GetDataFromChild event, passing the required data.

Run the application and click the button. On the clicking of the button, when we make the explicit call to the event from the user control, the parent page receives the notification through the UChild_GetDataFromChild method.

User_Control_Data_Passing.zip

How to use Converters in Windows phone app (Silverlight/WinRT)

ValueConverters can be used whenever we need to present data in an easy and controllable way such that it doesn’t interfere with other layers of the application.

Converters are called by the Data Binding mechanism whenever binding actually occurs (for example, when a control is notified about the change in the underlying property).

 

ValueConverters need to implement IValueConverter, a simple two-method interface. The two methods are

1) Convert – Modifies the source data before passing it to the target for display in the UI.

2) ConvertBack – Modifies the target data before passing it to the source object. This method is called only in TwoWay bindings.

For more reference you can see this link.

In this following blog post I shall be demonstrating you how to create an indexvalue
converter for your Windows phone app. The different steps you need to follow are

 

Step 1:

First create a class having the name IndexToColorConverter in your Project.

 

 

And add the following code to it as shown below.

 


 

Silverlight

WinRT  
Note: The only difference between Silverlight and WinRT is that the data type of parameter culture has been changed to string in WinRT.

 

Step 2:

Open the XAML page where you need to use this converter and add the following code in the namespace of the XAML page.


Note: Here Tips8 is the name of the Project. You need to replace it with your own project name.

 

Step 3:

Add the following code into PhoneApplicationPage page resources section in the XAML. It will create a Static resource within the XAML page with a specific key which will be used by the UI elements further.

 



  Note: The name of the key can be same as the Class name of color converter or something else. In order to avoid confusion we have kept both names as same.   Step 4: Now in the UI element just bind the property you wish to do so. For example in our project we have binded the Background Property and have assigned the IndexToColorConverter to it. The code for the following is

Note: Here index is the object property to which button is binded.

 

If you have any doubts regarding data binding you can refer to the following blog post.

http://windowsapptutorials.com/windows-phone/data-binding/data-binding-in-windows-phone-app-one-way-binding/


Reading and Writing in an Existing text file in Windows phone app (Silverlight / WinRT)

This is a small blog post in which I shall be explaining you how to read and write to an existing text file which is present locally in your project.

Let us suppose the text file is having the name myfile.text and is present under main root directory.

 


 

Step 1:

Now first thing you need to do is to set Build Action to Content. And, change Copy to Output Directory to Copy Always. This will ensure the file itself ships with your application. If it doesn’t, you won’t have a file to read.

 


 

Step 2:

Now you can read and write your text files easily as shown in the code below

 

Windows Phone Silverlight

Reading

 

 

Writing

 

 

WinRT

In WinRT you can access files in the local app data store using the “ms-appdata:///local/” protocol. To access files in the app package, use Windows. ApplicationModel. Package. Current. InstalledLocation.

Reading

 

 

Writing

 

 

Note: Suppose your file is not located in main directory and is located under the root folder Files as shown below.

 


 

Then file name would be


Note: You can use the same technique for an xml or json file.