FragmentExtensions.kt

TLDR

This file provides an extension function for the Activity class to register a callback that will be triggered when a fragment's view is destroyed.

Methods

onAndroidXFragmentViewDestroyed

This method is an extension function for the Activity class. It checks if the AndroidX Fragment Activity is available and if the current activity is an instance of the FragmentActivity class. If both conditions are met, it registers a FragmentManager.FragmentLifecycleCallbacks object with the support fragment manager. The callback's onFragmentViewDestroyed method is triggered when a fragment's view is destroyed, and it executes the provided block of code.

package leakcanary.internal

import android.app.Activity
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentActivity
import androidx.fragment.app.FragmentManager

private val hasAndroidXFragmentActivity: Boolean by lazy {
  try {
    Class.forName("androidx.fragment.app.FragmentActivity")
    true
  } catch (ignored: Throwable) {
    false
  }
}

internal fun Activity.onAndroidXFragmentViewDestroyed(block: () -> Unit) {
  if (!hasAndroidXFragmentActivity) {
    return
  }
  if (this is FragmentActivity) {
    supportFragmentManager.registerFragmentLifecycleCallbacks(
      object : FragmentManager.FragmentLifecycleCallbacks() {
        override fun onFragmentViewDestroyed(
          fm: FragmentManager,
          fragment: Fragment
        ) {
          block()
        }
      }, true
    )
  }
}