I have a requirement to trigger update automatically for enterprise app without user interaction can you please help me.
This is not possible with the current version of HockeySDK for iOS. However, since the SDK is open source, you can modify the code to your liking and use a custom build of the SDK in your app: http://github.com/bitstadium/HockeySDK-iOS/
It is possible to show a simplified version of the UI in form of a simple dialog using showDirectInstallOption.
Note though, that there will always be at least some user interaction because iOS itself requires user consent before installing a new side-loaded app or an update of such an app.