Hello,
I think that in this case you can use Xamarin. It is the best way to write advanced applications.
You can write your applications in C# code and it works on Android, iOS and Windows Phone.
Please see these links:
There are two ways for writing app:
1) Xamarin Forms: here you write one UI and one code. It is good for less complicated apps, for example if you want display some information from the web service.
Link:
http://developer.xamarin.com/guides/cross-platform/xamarin-forms/introduction-to-xamarin-forms/[
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2) Xamarin Android and Xamarin iOS: Here you write separate apps, you can use native UI controls for each platform. Your code is C# so you can use it between apps.
Link to iOS:
http://developer.xamarin.com/guides/ios/[
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Link to Android:
http://developer.xamarin.com/guides/ios/[
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Hope it will help.