Dear, sir.
Thanks for your invitation.
I have just read your requirement carefully and had very interesting in your project.
I have a lot of experiences in development of mobile application for chat App, messaging, social networking, restaurant reservations ,ADS, Push Notification, Google Map, and so on.
No problem.
Of course, I know you could be in doubt about my real ability.
It would be important for me to prove my ability through real project.
I hope this project would be the first step in long term partnership with you.
If you trust and award this job to me, I can be trusted to do the work well on high quality and schedule time.
You may rest assured that we shall honor our commitment.
I await you favorite reply with interesting.
Best regards.
Chai.