Interactive Toasts and Windows Phone 8.1

Windows 10 brings a whole range of new APIs and functionality for building apps. However in the phone space it’s important to be mindful that there are a lot more Windows Phone 8.1 devices in use than Windows 10. Many (but not all) will get an update to Windows 10. A lot of clients are keen on supporting 8.1 to cover the largest group (as an 8.1 app will just run on 10). Of course your users on Windows 10 may miss out on cool features in this way unless you are prepared to maintain both 8.1 and 10 versions of your app. There are a number of areas of the Charming Apps libraries which support “lighting-up” of functionality. That means exposing Windows 10 APIs to Windows 8.x projects. In some cases this is a remapping of existing functionality from an old-style API to one which is source compatible with UWP. In other cases there is functionality which is just not there on 8.x but you can make it available when your app is run on a Windows 10 device.

In order to support this a bit of Reflection is required but we’ve hidden that messy stuff for you – you just call the same APIs and get graceful failure or the “light-up” experience when running on Windows 10. For many of these APIs the Charming Apps library provides iOS and Android implementations while exposing the same UWP API surface. There are a number of possible ways of detecting whether the device at runtime is running Windows 10. One of these is to use:-

if (InTheHand.Foundation.Metadata.ApiInformation.IsApiContractPresent("Windows.Foundation.UniversalApiContract", 1))

Another is to check:-


(caveat – On 8.x we can return only Major.Minor.0.0 versions)

One of the new features in Windows 10 is the interactive toast notification. There is no API change to set these locally – it just requires a different XML template. So once you’ve checked your OS version you can switch between a traditional dumb toast or an interactive one such as:-

string xml = "<toast launch=\"yourstring\"><visual><binding template=\"ToastGeneric\" ><text>Big text</text><text>smaller text</text></binding></visual>"
                    + "<actions><input id=\"time\" type=\"selection\" defaultInput=\"2\"><selection id=\"1\" content=\"Breakfast\"/><selection id=\"2\" content=\"Lunch\"/><selection id=\"3\" content=\"Dinner\"/></input>"
         	    + "<action activationType=\"foreground\" content=\"Primary Action\" arguments=\"primary\"/><action activationType=\"foreground\" content=\"Secondary Action\" arguments=\"secondary\"/></actions>"
                    + "</toast>";

Notice that I’ve specified foreground activation. In a UWP project you’d also have the option of background activation where a background task is launched to carry out an action. In the case of foreground activation the system calls your app’s OnActivated method. However this is where it gets a bit more fun. The ActivationKind is not specified in Windows Phone 8.1, nor is the ToastNotificationActivatedEventArgs which is passed through. However the value of ActivationKind.ToastNotification is documented as 1010. The event args contains two items of interest, the Argument – the action which was selected and UserInput which is a string keyed dictionary of input id and selection id or input id and text entered in the case of a text field. I’ve added the following code in my OnActivated method to build up a string containing these values which can be passed to the applications main page using rootFrame.Navigate:-

	    string navigationParameter = null;

            switch (args.Kind)
                case (ActivationKind)1010: //ToastNotification:
                    StringBuilder sb = new StringBuilder();
                    IDictionary<string,object> selections = (IDictionary<string,object>)args.GetType().GetRuntimeProperty("UserInput").GetValue(args);
                    if (selections.Count > 0)
                        foreach (KeyValuePair<string, object> pair in selections)
                            sb.Append(pair.Key + "=" + pair.Value.ToString() + "&");

                        //remove trailing &
                        sb.Length -= 1;
                    navigationParameter = sb.ToString();

This is just another way of adding value to the user while still maintaining a Windows Phone 8.1 codebase. If you later update your app to Windows 10 it’s very easy to do without much alteration to your code. You don’t even have to go as far as adding interaction to your toasts but you could use this technique of detecting the OS version and simply use the new toast templates.
There are other areas of the Charming Apps libraries which “light-up” when running on Windows 10. For example there is a UWP style Clipboard API which just works on Windows 10 whereas the separate Clipboarder app is required for Windows Phone 8.1 (not Silverlight).