Dear sir.
I am a professional mobile app developer and have full experience for 6 years.
I read your project description carefully and I can understand what you want.
So now I can start your project and until you are satisfy, I will provide full service and do my best for you.
Please contact me.
I value my credit and will be kept the promise with you.
I hope you agree my proposal and will be accomplish it quickly and quality so that you 're satisfy about it.
Thanks very much.