Instance retaining¶

Sometimes it might be necessary to preserve state or data in a component when it gets destroyed. This commonly used in Android when configuration changes occur. The ComponentContext interface extends the InstanceKeeperOwner interface, which provides the InstanceKeeper - a multiplatform abstraction for instances retaining. It is provided by Essenty library (from the same author).

The decompose module adds Essenty's instance-keeper module as api dependency, so you don't need to explicitly add it to your project. Please familiarise yourself with Essenty library, especially with the InstanceKeeper.

Usage example¶

import com.arkivanov.decompose.ComponentContext
import com.arkivanov.essenty.instancekeeper.InstanceKeeper
import com.arkivanov.essenty.instancekeeper.getOrCreate

class SomeComponent(
    componentContext: ComponentContext
) : ComponentContext by componentContext {

    private val someLogic = instanceKeeper.getOrCreate(::SomeLogic)

    /*
     * Instances of this class will be retained.
     * ⚠️ Pay attention to not leak any dependencies.
     */
    private class SomeLogic : InstanceKeeper.Instance {
        override fun onDestroy() {
            // Clean-up
        }
    }
}