viewModelScope

Scopes in ViewModels

class MyViewModel : ViewModel() {

    /**
     * This is the job for all coroutines started by this ViewModel.
     * Cancelling this job will cancel all coroutines started by this ViewModel.
     */
    private val viewModelJob = SupervisorJob()
    
    /**
     * This is the main scope for all coroutines launched by MainViewModel.
     * Since we pass viewModelJob, you can cancel all coroutines 
     * launched by uiScope by calling viewModelJob.cancel()
     */
    private val uiScope = CoroutineScope(Dispatchers.Main + viewModelJob)
    
    /**
     * Cancel all coroutines when the ViewModel is cleared
     */
    override fun onCleared() {
        super.onCleared()
        viewModelJob.cancel()
    }
    
    /**
     * Heavy operation that cannot be done in the Main Thread
     */
    fun launchDataLoad() {
        uiScope.launch {
            sortList() // happens on the background
            // Modify UI
        }
    }
    
    // Move the execution off the main thread using withContext(Dispatchers.Default)
    suspend fun sortList() = withContext(Dispatchers.Default) {
        // Heavy work
    }
}

use viewModelScope

class MyViewModel : ViewModel() {
  
    /**
     * Heavy operation that cannot be done in the Main Thread
     */
    fun launchDataLoad() {
        viewModelScope.launch {
            sortList()
            // Modify UI
        }
    }
  
    suspend fun sortList() = withContext(Dispatchers.Default) {
        // Heavy work
    }
}