[Xamarin Interface - IOS/Android] Example > APP Dev

Some example code:

https://forums.xamarin.com/discussion/104922/how-to-set-get-the-app-version-number-and-build-for-cross-platform 

In your PCL define an interface like this:

namespace Your.Namespace.Interfaces

{

    public interface IAppVersion

    {

        string GetVersion();

        int GetBuild();

    }

}

And implement it like this in your platform projects:

IOS:

[assembly: Xamarin.Forms.Dependency(typeof(Your.Namespace.iOS.Version_iOS))]

namespace Your.Namespace.iOS

{

    public class Version_iOS : IAppVersion

    {

        public string GetVersion()

        {

            return NSBundle.MainBundle.ObjectForInfoDictionary("CFBundleShortVersionString").ToString();

        }

        public int GetBuild()

        {

            return int.Parse(NSBundle.MainBundle.ObjectForInfoDictionary("CFBundleVersion").ToString());

        }

    }

}

Android:

[assembly: Xamarin.Forms.Dependency(typeof(Your.Namespace.Droid.Version_Android))]

namespace Your.Namespace.Droid

{

    public class Version_Android : IAppVersion

    {

        public string GetVersion()

        {

            var context = global::Android.App.Application.Context;

            PackageManager manager = context.PackageManager;

            PackageInfo info = manager.GetPackageInfo(context.PackageName, 0);

            return info.VersionName;

        }

        public int GetBuild()

        {

            var context = global::Android.App.Application.Context;

            PackageManager manager = context.PackageManager;

            PackageInfo info = manager.GetPackageInfo(context.PackageName, 0);

            return info.VersionCode;

        }

    }

}

You can use this then in your pcl code:

string v = DependencyService.Get<IAppVersion>().GetVersion();

int b = DependencyService.Get<IAppVersion>().GetBuild();