ViewModelScope Extensions

MainViewModel.kt

class MainViewModel : ViewModel() {

   private fun doIoOperation() = onIO {
        // do your IO work here
   }
   
   private fun heavyCalculation() = onDefault {
        // do your calculation here
   }
   
   private lateinit var job: Job
    
   private fun cancelPreviousJobAndStartNewOne(){
       if (::job.isInitialized){
           job.cancel()
       } 
        
       // new job
       job = onIO { 
           // ....
       }
   }

}

NormalLaunching.kt

class MainViewModel : ViewModel() {

  init {
        viewModelScope.launch {
            // code to execute on main
        }

        viewModelScope.launch(Dispatchers.IO){
            // code to execute on IO
        }
    }

}

viewModelExtensions.kt

inline fun ViewModel.onMain(
    crossinline body: suspend CoroutineScope.() -> Unit
): Job {
    // by default, Dispatchers.Main is default dispatcher to viewModelScope
    return viewModelScope.launch() {
        body(this)
    }
}



inline fun ViewModel.onMainImmediate(
    crossinline body: suspend CoroutineScope.() -> Unit
): Job {
    // make sure to read documentation about immediate dispatcher, it can throw Exception!
    return viewModelScope.launch(Dispatchers.Main.immediate) {
        body(this)
    }
}


inline fun ViewModel.onIO(
    crossinline body: suspend CoroutineScope.() -> Unit
): Job {
    return viewModelScope.launch(Dispatchers.IO) {
        body(this)
    }
}


inline fun ViewModel.onDefault(
    crossinline body: suspend CoroutineScope.() -> Unit
): Job {
    return viewModelScope.launch(Dispatchers.Default) {
        body(this)
    }
}

inline fun ViewModel.onUnconfined(
    crossinline body: suspend CoroutineScope.() -> Unit
): Job {
    return viewModelScope.launch(Dispatchers.Unconfined) {
        body(this)
    }
}