Over the last month, I have gone back to “AlarmClock” app (my 3rd Windows Phone app from back in 2011). I have updated it to render time updates on live tile. In fact I am quite proud the mechanism I use. I additionally provided 50 downloadable font packs that users can choose from (purchasable in a set of 10).
The update mechanism was initially based on Silverlight Background Task. The tile update mechanism of course updates tile based on local time. However a user reported that when travelling between timezones, the tiles kept showing previous timezone times until the next background task run started pushing new ones based on new local time.
I deliberated on this and came to the conclusion that somewhere something was fishy.. its possible that Tile updates are actually scheduled on UTC as opposed to local time or maybe I just don’t understand it. Either way, I had to fix this issue
Solution 2: Fix for Timezone change
The new windows phone 8.1 introduced a bunch of new WinRT API that included API for Background task including those that run on Timezone change. So I dumped SL based Background Task and went full stream with WinRT component. Added 2 WinRT classs on for Timer and another for Timezone and this worked great.
Another user wanted the clock and tile updates to support multiple Timezones – wanted to pin Hong Kong and Seattle. My app so far only supported local device timezone.
Soluion 3 – Multiple Timezone support
.NET 4.5 comes with TimeZoneInfo class.This provides a nice method GetSystemTimeZones which lists all timezones and make it possible to convert between those. However Windows Phone .NET Runtime does not come with this and there is not suitable WinRT API either. Yay!!
Oren Novotny created a good Win32 wrapper which works on both WP8, WP81, SL81 and WinRT
I fired up Nuget Package Manager and searched for timezone..found Timezone conversion between WinRT and PCL.. Added a reference to the App and reworked it to support user selectable timezone etc. This required me to select target between x86 and ARM – any CPU no longer an option.
Next step?? Add Timezone helper reference to WinRT component. Bang bang bang.. nugget sorted it all out.. that was easy.. modified the background processor to update all tiles with correct timezone times!! nice :) What could possibly go wrong ?
Hit F6, (Old school.. modified VS 2013 to build o F6 like before).. all good. Hit F5… wait for it !!!!
Runtime exception – File not found
System.Runtime.InteropService.. quick search showed reference conflict..
Step 1) Set WinRT component to x86 instead of Any CPU.. maybe that will do the trick!!!
Nope far from it… Result
System.BadImageFormatException thown when trying to run the app.
Step 2) Download code and make a part of existing WinRT component..
Nope still the same error(s)
While deliberating, realised that I called code from Background Task directly from my app.. 3rd trial
Remove calls to code in Background Task from App
Nuget Reference to App
Code within WinRT component for internal use
App – x86 / ARM target
WinRT component – Any CPU tagt
Bingo.. It all work as advertised!!
Took me day to figure try out various options