Get battery level on Windows and iOS

In Windows Phone 8.1 a new API was added to both retrieve the current battery level as a percent of fully charged and also handle an event fired when the value changed. Sadly this API is not common across this and “big” Windows.

In a couple of projects I’ve needed to retrieve the battery level periodically so that the app can perform different actions depending on the device state. This encouraged me to “port” the API to Xamarin iOS which does provide the same capability but in a platform-specific way through UIDevice. When it came to Windows 8.1 there was an interesting problem. There is a native API you can call to query the battery level, however you can’t call it from within an app you submit to the public Windows store because the API is not on the Whitelist (http://msdn.microsoft.com/en-us/library/windows/apps/br205757.aspx). For my initial use this was okay because the app was to be privately distributed. Sadly I don’t have a solution for a Store app. You may have seen various Store apps for battery which get around the problem by asking you to install a desktop “service” which retrieves the value  and passes it to the store app. Why the API was not added to Windows 8.1 at the same time as Phone 8.1 is odd with the big push on “universal apps”, at the bare minimum the native API should have been whitelisted. It returns no identifiable information and is read-only. There are plenty of more malicious things that could be done via supported APIs…

Given the caveat mentioned above I decided to release my code in case it is of use to others. The iOS version is fully functional and can be use for public apps. An Android implementation will follow in due course…

https://www.nuget.org/packages/InTheHand.Devices.Power/