IOS Youtube Player: Toggle YouTube Player Full Screen in iOS with Custom Controls

I have a requirement to create custom controls for Youtube player in iOS. I have used UIWebview to play YouTube videos. I have hidden controls by default using a flag 'controls':0

. I can display all actions like play, pause, etc. Using java script api with my UIButtons. But I cannot figure out how to programmatically toggle full screen mode using my custom button.

Any help is appreciated.