2019 DevDay How To Reduce Android App Launch Time by Scoping Your Dependencies Using Koin DI > Aldo Kelvianto Wachyudi > LINE Indonesia Android Engineer

Introduction > I've been working on LINE Today App project since 2018 > LINE Today App version is now v4.1 > LINE Today features: Read news, watch videos, listen to podcast, give comments > How do we maintain more features in the future?

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More Features More Objects More Modules

Dev Day Schedule App List of Speakers Show News

> SpeakerActivity > SpeakerModule // 7 objects List of Speaker News > NewsActivity > NewsModule // 6 objects Features, Activity, Module

How To Inject These Modules?

What's the Problem? > Production app has more than 2 modules and 15 objects > If we have 200 objects, it takes ~> 16.7 ms (skipped frame!) > Those objects linger in memories, used or not > Not ready to scale > Hard to maintain the code. Minor changes cause unexpected side-effect

How To Improve This? > SpeakerActivity don't need NewsActivity objects, vice versa > Scope the objects "Scope is a fixed duration of time or method calls in which an object exists."

Injection Result - Unscoped // 2 objects from context // 7 objects from speaker module // 6 objects from news module total 15 registered definitions load modules in 1.717 milliseconds

Injection Result - Scoped // 73% faster! // Only binds 2 objects (Application and Context) total 15 registered definitions load modules in 0.448 milliseconds

Scoping Benefit > Faster app launch time > The objects exist only when they're used > Ready to scale > More maintainable code

How To Scope Module? Unscoped

How To Scope Module? Scoped

Summary > In Koin, Scope can ties to Activity, Fragment, ViewModel, or custom (define yourself) > It’s a concept, can be applied to any DI framework > In Dagger, you can use Scope annotation or Subcomponents > Code is available on https://github.com/aldoKelvianto/KoinScopeDemo