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Ahmed El-Helw October 21, 2022 Productive Mobile Development Tips and Tricks for Productive Mobile Development

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Factors affecting Speed Things to Consider • Distractions

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Factors affecting Speed Things to Consider • Distractions • Communication Problems

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Factors affecting Speed Things to Consider • Distractions • Communication Problems • Con fl icting Priorities

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Factors affecting Speed Things to Consider • Distractions • Communication Problems • Con fl icting Priorities • Technical Debt

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Factors affecting Speed Things to Consider • Distractions • Communication Problems • Con fl icting Priorities • Technical Debt • Production Fires

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Source

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Factors affecting Speed Things to Consider • Distractions • Communication Problems • Con fl icting Priorities • Technical Debt • Production Fires • Hardware

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Source

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Process Bottlenecks Mobile Bottlenecks • Company release process • Application store review process • Application store rejections • Adoptions take time

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Experiments and Toggles

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Tim Campos “Data wins Arguments”

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Customer Behavior Understanding and Monitoring Customer Behavior • Dashboards • critical business statistics • conversion funnels • Slice by application version • Alerts

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Dealing with Problems How to React to Problems • Ignore it for now • Hot Fix in Production • Release takes time • Adoption takes time • Risky

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Source

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What if we just turn it off?

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Other Considerations Things to Keep in Mind • Be mindful about: • The e ff ect of experiments on each other • The e ff ect of feature fl ags on each other • Dead Experiments increase Technical Debt • Can tooling help here?

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Data

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Data Some odds and ends about Data • Building trust with Customers • Compliance • App Stores • Governments

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Policy Changes are often a Surprise

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MetaFilter via Forbes Article “If you're not paying for it, you become the product”

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As a company grows, so too does the value of its data

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Structuring Code

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Modularization Structuring Code • Have a set of rules and guidelines • Split APIs and Implementation

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Modularization Structuring Code / / in profile-api module interface Profile { fun isLoggedIn(): Boolean fun currentCustomer(): Customer? fun editCustomerIntent(context: Context): Intent? }

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Modularization Structuring Code / / in profile module class ProfileImpl constructor( private val profileRepository: ProfileRepository ) : Profile { override fun isLoggedIn(): Boolean = currentCustomer() != null override fun currentCustomer(): Customer? { return profileRepository.provideCustomer() } override fun editCustomerIntent(context: Context): Intent { return Intent(context, EditProfileActivity : : class.java) } }

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Modularization Structuring Code / / in profile-noop module class ProfileNoop : Profile { override fun isLoggedIn(): Boolean = true override fun currentCustomer(): Customer = Customer(123L, "Test") override fun editCustomerIntent(context: Context) = null }

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Modularization Structuring Code fun provideProfile(): Profile { return if (isDebug) { ProfileNoop() } else { ProfileImpl(ProfileRepository()) } }

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Benefits of Modularization Structuring Code • Better isolation of Features • Easier sharing • Easier and faster testing • Ability to stub implementations • Standalone apps

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Sharing Code Across Platforms

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How do we Save Time?

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Options Sharing Code Between Platforms • Frameworks that handle Everything • Do it yourself Tooling

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React Native

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5 Part Series React Native at Airbnb

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Flutter

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Frameworks that Handle Everything Sharing Code Between Platforms • Pros • Potentially easier to hire for • Write once, use everywhere • Faster development (hot reload, etc) • Potential for hot loading code

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Frameworks that Handle Everything Sharing Code Between Platforms • Cons • Need to explicitly build separate UI for iOS and Android • Doesn’t “feel” native irrespective • New platform features are di ffi cult to adopt - need to wait • Overhead on binary size • Rejections Likely

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C/C++

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C/C++ Sharing Code Between Platforms • Pros • High performance • Easier to obfuscate code

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C/C++ Sharing Code Between Platforms • Cons • Di ffi cult • Still have to handle di ff erences between platforms • Custom development environment

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Dropbox Blog Post The (not so) hidden cost of sharing code between iOS and Android

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Kotlin Multiplatform

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Kotlin Multiplatform Sharing Code Between Platforms • Pros • Completely native • Easy to learn for engineers writing Swift • Lots of third party libraries • Backed by JetBrains and Google • Supports a plethora of platforms

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Kotlin Multiplatform Sharing Code Between Platforms • Cons • iOS inter-op with Objective-C instead of Swift • Convincing iOS Engineers is Di ffi cult • Tooling • Still in the process of maturing

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Alternatives

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Alternatives Sharing Between Platforms • Code generation • Annotation processors • Compiler plugins, Gradle plugins • Templating code generators (Stencil, …)

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Sharing Code Generating Code component: name: Car fields: make: string model: string vin: string vendor: string

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Sharing Code Generating Code data class Car( val make : String, val model : String, val vin : String, val vendor : String, )

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Sharing Code Generating Code struct Car { let make: String let model: String let vin: String let vendor: String }

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Sharing Code Generating Code data class {{ component.name }}( {% for key, value in component.fields %} val {{ key | lowerFirstLetter }} : {{ value | upperFirstLetter }}, {% endfor %} )

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Sharing Code Generating Code struct {{ component.name }} { {% for key, value in component.fields %} let {{ key | lowerFirstLetter }}: {{ value | upperFirstLetter }} {% endfor %} }

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What to Share

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Things to Share Sharing Between Platforms • Analytics • Business Logic • Vocabulary • Architecture • Design System • Versioning • Release Process

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CI/CD

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Catching Mistakes Early Saves Time and Money

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First Lines of Defense Catching Issues Early • The build process itself • Automated checkers • Lint • Code styling enforcers • Code smell detection • Coverage • Code Review helps catch issues early

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Tests Catching Issues Early • Tests • Unit Tests • Integration Tests • On-Device Integration Tests (“UI Tests”) • Screenshot Tests • Maestro Tests

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Expose Hidden Changes Catching Issues Early • Transitive Dependencies

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Dependency-Diff-Tldr Exposing Hidden Changes Upgraded Dependencies 
 com.squareup.moshi:moshi-adapters:1.14.0, (changed from 1.13.0) 
 org.jetbrains.kotlin:kotlin-stdlib:1.7.20, (changed from 1.7.10) 
 org.jetbrains.kotlin:kotlin-stdlib-common:1.7.20, (changed from 1.7.10) 
 org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.7.20, (changed from 1.7.10) 
 org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.7.20, (changed from 1.7.10)

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Expose Hidden Changes Catching Issues Early • Transitive Dependencies • Binary Size

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Diffuse Exposing Hidden Changes │ compressed │ uncompressed ├───────────┬───────────┬──────────┼───────────┬───────────┬────────── APK │ old │ new │ diff │ old │ new │ diff ──────────┼───────────┼───────────┼──────────┼───────────┼───────────┼────────── dex │ 11.6 MiB │ 11.6 MiB │ -107 B │ 29.4 MiB │ 29.4 MiB │ -336 B arsc │ 1.8 MiB │ 1.8 MiB │ -992 B │ 1.8 MiB │ 1.8 MiB │ -988 B manifest │ 5.6 KiB │ 5.6 KiB │ +1 B │ 27.6 KiB │ 27.6 KiB │ 0 B res │ 1.1 MiB │ 1.1 MiB │ -3 KiB │ 1.3 MiB │ 1.3 MiB │ -4.8 KiB asset │ 404.2 KiB │ 404.2 KiB │ 0 B │ 678.6 KiB │ 678.6 KiB │ 0 B other │ 173.6 KiB │ 173.1 KiB │ -550 B │ 336.9 KiB │ 335.7 KiB │ -1.3 KiB ──────────┼───────────┼───────────┼──────────┼───────────┼───────────┼────────── total │ 15.1 MiB │ 15.1 MiB │ -4.6 KiB │ 33.5 MiB │ 33.5 MiB │ -7.4 KiB

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Expose Hidden Changes Catching Issues Early • Transitive Dependencies • Binary Size • Binary compatibility breaking changes

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Binary Compatibility Validator Exposing Hidden Changes FAILURE: Build failed with an exception. * What went wrong: Execution failed for task ':miniapp:apiCheck'. > API check failed for project miniapp. --- /bitrise/src/miniapp/api/miniapp.api +++ /bitrise/src/miniapp/build/api/miniapp.api @@ -16,6 +16,7 @@ public abstract interface class com/careem/superapp/lib/miniapp/ IntegrationDependencies { public abstract fun provideEventBus ()Lcom/careem/ superapp/lib/eventbus/EventBus; + public abstract fun provideLocationPickerSdk ()Lcom/ careem/globalexp/locations/api/LocationPickerSdk; } You can run :miniapp:apiDump task to overwrite API declarations

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Expose Hidden Changes Catching Issues Early • Transitive Dependencies • Binary Size • Binary compatibility breaking changes • Permissions

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Expose Hidden Changes Tooling • di ff use • dependency-di ff -tldr / dependency-guard • metalava-gradle / binary-compatibility-validator

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Releases Catching Issues Early • Beta program • Staged rollouts to production • Release early, release often • Release should be a train, not a bus

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Dashboards and Data Catching Issues Early • Do not hide crashes • Handled exceptions and breadcrumbs are useful • Developer and performance metrics • Development Tooling • Chucker • LeakCanary

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Engineering Culture

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Engineers are Humans Engineering Cultures • All humans make mistakes • Blame is bad • Blame is the enemy of ownership

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When Issues Arise Engineering Cultures • How could this have been prevented? • Why was this not caught earlier? • Combine fi xes with veri fi cation tests. • Post mortem

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Keep Learning and Improving

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Focus on Impact

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Android Mid Level Roles Android Senior Level Roles We are hiring! 🤖

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Thank You