Viewmodel

To use viewmodel first need to add gradle dependency

implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0' 

make new kotlin file with appropriate viewmodel name

class SampleViewModel : ViewModel()

Add init block and override onCleared. Add log statements to both

Create a field for the viewmodel class we created in the recquired activity

private lateinit var sampleviewmodel: SampleViewModel

Inside oncreate of class or fragment initialize viewmodel

viewModel = ViewModelProviders.of(this).get(GameViewModel::class.java)

now place the logic codes in the viewmodel class

view model should never hold references to activities or fragments.

UI controller(activity) should be as simple as possible