'by viewModels()' Kotlin property delegate unresolved reference

I'm trying to implement viewmodel with kotlin. First I added the needed dependecies:

implementation 'androidx.appcompat:appcompat:1.1.0'
implementation 'androidx.core:core-ktx:1.2.0'
// ViewModel
implementation "androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0"
// Annotation processor
kapt "androidx.lifecycle:lifecycle-compiler:2.2.0"

Then I created a simple viewmodel:

class MyViewModel: ViewModel() {
val greeting = "Hello World"
}

But when I tried to access the view model from the activity with kotlin property delegate:

val model by viewModels<MyViewModel>()

The compiler does not resolve `viewModels`. I don't know what the problem is. Did I miss something?

For me the solution above this not work.

I needed to import :

implementation 'androidx.navigation:navigation-fragment-ktx:2.3.5'

Add these dependencies:

implementation "androidx.activity:activity-ktx:$activity_version"
implementation "androidx.fragment:fragment-ktx:$fragment_version"

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For me the solution above this not work.

Add this dependency: :

implementation 'androidx.navigation:navigation-ui-ktx:2.3.5'

Add This dependency :

implementation "androidx.lifecycle:lifecycleviewmodel:2.2.0"

**Resolved this error**, using below dependency in module-level **build.gradle**

implementation 'androidx.navigation:navigation-fragment-ktx:2.3.5'
implementation 'androidx.navigation:navigation-ui-ktx:2.3.5'

**OR**

implementation 'androidx.lifecycle:lifecycle-extensions-ktx:2.2.0'
implementation 'androidx.activity:activity-ktx:1.4.0'
implementation 'androidx.fragment:fragment-ktx:1.3.6'

I have also added below dependency to implement **ViewModel** in **Kotlin**

implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.3.1'
implementation 'androidx.lifecycle:lifecycle-runtime-ktx:2.3.1'


My module-level **build.gradle** start as per below

plugins {
id 'com.android.application'
id 'kotlin-android'
}

In my case, I was just using the wrong type of Activity. I had an `android.app.Activity` instead of an `androidx.appcompat.app.AppCompatActivity`.`viewModels()` is only available in the latter.

For me, I was having the following dependencies:
```
implementation 'androidx.activity:activity-compose:1.5.0'
```
but still I faced this same error.


The reason was that `by viewModels()` must be called inside the `onCreate()`:
```
class MainActivity : ComponentActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)

val customViewModel: MyViewModel by viewModels()

setContent {
AppTheme {
Surface() {
MyApp(customViewModel = customViewModel)
}
}
}
}
}
```
and not in any other composable function. But I was trying to calling it from `MyApp()` composable function. Hence the error.

It depends, on how you are using ViewModel. If you don't use fragments, this is enough to resolve "Unresolved reference: viewModels" for activity.
```
// ViewModel
implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.5.1'
implementation 'androidx.activity:activity-ktx:1.6.1'
```
```
// is to add the dependency on Fragment
implementation 'androidx.fragment:fragment-ktx:1.2.5'
```

```
// is to add the dependency on Activity
implementation 'androidx.activity:activity-ktx:1.1.0'
```