Searching contacts

To the developers,

I am in need of some real help. Within my app, I need to include a search bar that will search the default contact list on the android phone and return a string variable containing the phone number of the selected person. This is an essential feature to my app I am developing, one of the only remaining essential components need to complete the app, and so I would deeply appreciate it if anyone could type the snippet of code, or better yet direct me to a tutorial, regarding this matter. Thank you in advance, and I hope to see your answers soon