A cross-platform mobile application is an application that runs on multiple mobile platforms (Android, iOS). Several frameworks, have been proposed to simplify the development of cross-platform mobile applications and, therefore, to reduce development and maintenance costs. Between them, the cross-compiler mobile development frameworks, such as Xamarin from Microsoft, transform the application's code written in intermediate (aka non native) language to native code for each desired platform. However, to our best knowledge, there is no much research about the advantages and disadvantages of the use of those frameworks during the development and maintenance phases of mobile applications. The objective of this paper is twofold. Firstly, to present two datasets of questions and answers (Q&A) related to the development of mobile applications using Xamarin. Secondly, to show their usefulness, we present a replication study for discovering the main discussion topics of Xamarin development. We created the two datasets by mining two Q&A sites: Xamarin Forum and Stack Overflow. Then, for discovering the main topics of the questions from both datasets, we replicated a study that applies Latent Dirichlet Allocation (LDA). Finally, we compared the discovered topics with those topics about general mobile development reported by a previous study. Our datasets have 85,908 questions mined from the Xamarin Forum and 44,434 from Stack Overflow. Between the main topics discovered from those questions, we found that some of them are exclusively related to Xamarin and Microsoft technologies such as the design pattern "MVVM". Both datasets with Xamarin-related Q&A can be used by the research community for understanding the main concerns about developing cross-platform mobile applications using Xamarin. In this paper, we used it for replicating a studying about topic discovering.