Trigger Search On IPhone Mobile App

I have a list screen in iPhone mobile application and there is a text search field on top. My requirement is to trigger the search using appropriate IPhone keyboard key. Please suggest the keyboard key that should trigger the search and also how to detect the key press event for that key in order to trigger the search client action? 

Note - The application is targeted to run on iPad too. 

I have gathered some information here, which I hope will be helpful.

I think you can use the sample module found here:

and conduct iphone tests by gathering the information found in these other forums.

I'm sorry for being currently unable to perform these tests, maybe using the right event with the right function will work