This paper presents a model reverse-engineering approach, combined with automatic testing, for mobile applications that belong to the GUI application category. Our method covers the interfaces of an application to incrementally infer a formal model expressing the navigational paths and states of the application. The main contributions of this paper can be summarised as follows: we propose an original definition of the GUI application model which eases the limitation of the application exploration. Then, we propose an algorithm based upon the Ant Colony Optimisation technique which offers the possibility to parallelise the application exploration and to conceive any application exploration strategy as desired. Finally, our approach is experimented on Android applications and compared to other tools available in the literature.