Dagger2 and Android Lifecycle with Kotlin

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1. Dagger2 and Android Lifecycle with Kotlin @takuji31
2. @takuji31 (Takuji Nishibayashi)
3. Loves Kotlin
4. Dagger2
5. de facto standard of DI container for Android (may be)
6. Compile )me dependency resolu)on
7. Scoped singleton
8. Example of use
9. Inject context
10. Inject presenter
11. Inject Realm
12. Two Headaches for Android of the life cycle with injected instances
13. Headaches • Handle lifecycle events • Retain some instance during configura7on change
14. Handle lifecycle events
15. Stop UI refreshing in presenter
16. Cancel API request
17. Close Realm instance
18. Unsubscribe RxJava subscrip1on
19. Retain some instance during screen rota0on
20. Keep API request
21. Loaded model instances
22. But, Loader is difficult !
23. Solu%on
24. Headaches • Handle lifecycle events ! • Retain some instance during configura7on change
25. Create lifecycle provider
26. Lifecycle provider interface ActivityLifecycle { fun onCreate(savedInstanceStete: Bundle?) {} fun onSaveInstanceState(outState: Bundle?) {} fun onDestroy() {} //... }
27. Lifecycle provider object Lifecycles { fun activity(vararg lifecycles: ActivityLifecycle): ActivityLifecycle { return object : ActivityLifecycle { override fun onCreate(savedInstanceStete: Bundle?) { lifecycles.forEach { it.onCreate(savedInstanceStete = savedInstanceStete) } } override fun onStart() { lifecycles.forEach { it.onStart() } } //... } }
28. Provide Lifecycle provider @Module class UserModule() { @Provides @PerActivity fun lifecycle(presenter: UserPresenter) : ActivityLifecycle { return presenter //or return Lifecycles.activity(presenter, some, lifecycle, objects) } }
29. Use lifecycle provider class UserActivity : AppCompatActivity() { @Inject lateinit var lifecycle : ActivityLifecycle var component : UserComponent by Delegates.notNull() override fun onCreate(savedInstanceState: Bundle?) { lifecycle.onCreate(savedInstanceStete = savedInstanceState) } override fun onDestroy() { lifecycle.onDestroy() } }
30. Headaches • Handle lifecycle events • Retain some instance during configura7on change !
31. Use retain fragment for keep component
32. Retain fragment class UserComponentFragment : Fragment() { var component: UserComponent? = null init { retainInstance = true } companion object { val TAG = "UserComponentFragment" } }
33. Use retain fragment class UserActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { var storeFragment = supportFragmentManager .findFragmentByTag(UserComponentFragment.TAG) as? UserComponentFragment if (storeFragment == null) { storeFragment = UserComponentFragment() supportFragmentManager .beginTransaction() .add(storeFragment, UserComponentFragment.TAG) .commit() } if (storeFragment.component == null) { //init component } storeFragment.component.inject(this) } }
34. see. takuji31/Dagger2Android
35. Enjoy Dagger2 and Android life !