Dialog helper for Universal Apps the easy way

Today I read Joost van Schaik’s blog post called A behavior to show a MessageDialog from a MVVMLight viewmodel in Universal apps–with callbacks. I am not a MVVMLight guy (I use Caliburn.Micro) and I personally use an approach that uses a little less code, employing a helper class.

Helper class

/// <summary>
/// Helper class for showing message dialogs
/// </summary>
public static class DialogHelper
{
    /// <summary>
    /// Shows a dialog with given message and ok/cancel buttons. 
    /// </summary>
    /// <param name="message">Message</param>
    /// <param name="title">Title</param>
    /// <param name="okText">OK text (optional)</param>
    /// <param name="cancelText">Cancel text (optional)</param>
    /// <returns>True if ok pressed, false otherwise</returns>
    public static async Task<bool> ShowMessageDialog(string message, string title, string okText, string cancelText)
    {
        bool result = false;
        var dialog = new MessageDialog(message, title);

        if (!string.IsNullOrWhiteSpace(okText))
        {
            dialog.Commands.Add(new UICommand(okText, cmd => result = true));
        }

        if (!string.IsNullOrWhiteSpace(cancelText))
        {
            dialog.Commands.Add(new UICommand(cancelText, cmd => result = false));
        }

        await dialog.ShowAsync();            
        return result;
    }
}

with a simple usage in ViewModel

[Read More]

Creating a fake splashscreen for your Universal App

Sometimes you may want your app to display the startup splashscreen a bit longer, so you can initialize or fetch some data necessary for the app to run. To achieve this, you can create a fake splaschreen, a View that looks just like the splashscreen, does all the work and redirects to the real main View afterwards.

In theory, it is quite simple:

  • Create a SplashScreenView with just the right background and the splashscreen image
  • Set the app to display SplashScreenView at startup
  • Do all the initializing and data fetching in SplashScreenViewModel and redirect to there real MainView

This works quite well with Windows 8.1, but on Windows Phone 8.1 there is a problem. When you run the Windows Phone 8.1 app, you will see a page transition happen between the real splashscreen and your SplashScreenView. This looks strange, so it is better to get rid of it.

[Read More]

Why Universal Apps as not as universal as you may think

I have been developing Windows Phone apps for a few years now, always sticking to Silverlight and keeping using Silverlight also after Microsoft announced the WinRT flavor of Windows Phone apps and the so called Universal Apps. The Windows Phone 8.0 and 8.1 Silverlight APIs have some limitations, but are now well known do not contain many bugs. They are the safe choice if you want to create a Windows Phone apps. And do not forget that there are still many device running Windows Phone 8 (like Verizon customers in the US) that never got the 8.1 updated promised to everyone during the summer.

Really universal?

Windows Phone 8.1 XAML and Universal Apps included WinRT APIs that have many problems, including some that there is no solution for. I used the WinRT APIs when creating first Windows 8 apps about 2 years ago, so I am not new to the APIs. I have not touched the WinRT APIs again until recently, because there was no demand for Windows 8 or Windows 8.1 apps. Why would it? People use Windows 8 or 8.1 but do not care about Metro apps, they give them no value compared to “normal” Win32 and Windows tablets are practically non-exists (expect for the Surface tablets owned by few programmers and maybe no one else).

[Read More]

REST service base class for Windows Phone 8.1 XAML apps

Communicating with a JSON based REST service is a task that many Windows Phone apps have to do. My apps sure do it a lot so I came up with a base class that I use in all of them, put it on Github and created a Nuget package, so your apps could use it to.

The usage of this base class is simple. Create your service class and inherit from BaseRestService. The minimum you need to do to make it work is to override the GetBaseUrl() method to set the base url for all the requests. You can (but do not have to) also override the GetRequestHeaders() method to set the default request headers.

public class MyDataService: BaseRestService
{
  protected override string GetBaseUrl()
  {
    return "my base url";
  }
  
  protected override Dictionary<string, string> GetRequestHeaders()
  {
    return new Dictionary<string, string>
    {
      {"Accept-Encoding", "gzip, deflate"},
      {"Accept", "application/json"},
    };
  }
}

and you can now use the following protected methods

[Read More]

Detecting tablets and smartphones in ASP.NET

I recently worked on an ASP.NET application that needed to detect if users were coming from tablets or smartphones. The project used data from http://user-agent-string.info/ to do this detection, but the result were not really good. We needed a better solution, so I came up with using WURFL.

WURFL, the Wireless Universal Resource FiLe, is a Device Description Repository (DDR), i.e. a software component that maps HTTP Request headers to the profile of the HTTP client (Desktop, Mobile Device, Tablet, etc.) that issued the request. Adding WURFL to your ASP.NET application is easy thanks to the WURFL_Official_API Nuget package. The Nuget package also contains definition file, so you just need to update the Nuget package once in a while to get your definition file up to date.

[Read More]
asp  csharp