Mobile App Development
iOS, Android, cross-platform frameworks, app monetization
Should I use Swift or Objective-C for new iOS app development?
Apple officially recommends Swift for all new iOS development. Swift is faster to write, safer due to strong typing, and is the language Apple actively invests in. Objective-C remains supported for legacy codebases, but Swift has been Apple's primary language since 2014 and is required for many modern APIs. [Source: Apple Developer Documentation]
What is Xcode and what does it include for iOS development?
Xcode is Apple's official integrated development environment (IDE) for building apps across iOS, macOS, watchOS, and tvOS. It includes a code editor, Interface Builder, simulator, performance profilers (Instruments), and the Swift/Objective-C compilers. Xcode is free to download from the Mac App Store and is required to submit apps to the App Store. [Source: Apple Developer]
How do you submit an app to the Apple App Store?
To submit an app to the App Store, you need an Apple Developer Program membership ($99/year), a completed app built with Xcode, and an App Store Connect account. You upload the app binary via Xcode or Transporter, complete metadata, set pricing, and submit for Apple's review process, which typically takes 24–48 hours. [Source: Apple Developer]
How much does the Apple Developer Program cost?
The Apple Developer Program costs $99 USD per year for individuals and businesses, granting access to beta software, advanced app capabilities, and the ability to distribute apps on the App Store. A separate Apple Developer Enterprise Program costs $299/year for internal app distribution only. Non-profit organizations and educational institutions may qualify for free membership. [Source: Apple Developer]
How do you publish an app on the Google Play Store?
Publishing on Google Play requires a Google Play Developer account, a signed APK or Android App Bundle (AAB), and a completed store listing. You upload assets and the binary via the Google Play Console, set a content rating, configure distribution, and submit. Google typically reviews apps within a few hours to 7 days. [Source: Google Play Console Help]
How much does a Google Play developer account cost?
A Google Play developer account requires a one-time registration fee of $25 USD, granting permanent access to the Google Play Console to publish and manage Android apps. This is a lifetime fee, unlike Apple's annual $99 subscription. Organizations publishing free apps for non-profits may apply for fee waivers in some cases. [Source: Google Play Console Help]
When should you choose cross-platform development over native mobile development?
Cross-platform frameworks like Flutter and React Native are best when you need to target both iOS and Android with a single codebase, have limited resources, or are building apps without heavy platform-specific features. Native development (Swift for iOS, Kotlin for Android) is preferred for performance-critical apps, advanced hardware access, or platform-specific UI fidelity. [Source: Google Developers]
What is Flutter and who maintains it?
Flutter is an open-source UI toolkit developed and maintained by Google for building natively compiled applications for mobile, web, desktop, and embedded platforms from a single Dart codebase. It uses its own rendering engine (Skia/Impeller) rather than native UI components, enabling pixel-perfect consistency across iOS and Android without relying on platform widgets. [Source: Flutter.dev / Google]
What is React Native and how does it differ from Flutter?
React Native is an open-source framework maintained by Meta that lets developers build native iOS and Android apps using JavaScript and React. Unlike Flutter, which renders its own widgets, React Native bridges JavaScript to actual native platform UI components. This means React Native apps use native controls, while Flutter renders its own UI layer. [Source: Meta Open Source / React Native Docs]
What are the key technical differences between Flutter and React Native?
Flutter compiles Dart code to native ARM machine code and renders UI via its own graphics engine, giving it highly consistent performance. React Native uses a JavaScript bridge (or the newer JSI architecture) to communicate with native modules. Flutter generally offers superior rendering consistency; React Native has a larger JavaScript ecosystem and is easier for web developers to adopt. [Source: Flutter.dev / Google; Meta Open Source]
Should I use Kotlin or Java for new Android app development?
Google officially declared Kotlin its preferred language for Android development in 2019. Kotlin offers null safety, concise syntax, coroutines for asynchronous programming, and full interoperability with Java. All new Android Jetpack APIs and Google samples are Kotlin-first. Java remains fully supported, but new Android projects are strongly recommended to use Kotlin. [Source: Android Developers / Google]
What is Android Studio and what are its main features?
Android Studio is the official IDE for Android development, built by Google on IntelliJ IDEA. It includes a code editor with Kotlin/Java support, a visual layout editor, an Android Emulator, profiling tools, Gradle-based build system, and integrated support for Android Jetpack libraries. Android Studio is free and available for Windows, macOS, and Linux. [Source: Android Developers / Google]
What is the difference between an Android App Bundle (AAB) and an APK?
An APK (Android Package) is a self-contained installable file containing all app code and resources. An Android App Bundle (AAB) is a publishing format that lets Google Play dynamically generate optimized APKs tailored to each device's screen density, CPU architecture, and language, reducing download sizes. Google Play has required AAB for new apps since August 2021. [Source: Android Developers / Google]
What are Apple's App Store Review Guidelines and why do they matter?
Apple's App Store Review Guidelines are the official rules all iOS, macOS, watchOS, and tvOS apps must follow to be accepted on the App Store. They cover safety, performance, business practices, design, and legal compliance. Violations result in rejection or removal. Apple updates these guidelines regularly, and developers must comply or risk losing App Store distribution. [Source: Apple Developer]
What percentage of app revenue do Apple and Google take from developers?
Both Apple and Google take a 30% commission on most in-app purchases and paid app downloads. However, both platforms reduced the cut to 15% for developers earning under $1 million annually — Apple via its Small Business Program (since 2021) and Google via its similar program. Subscription revenue also drops to 15% after the first year on both platforms. [Source: Apple Developer; Google Play Console Help]
What are the main monetization strategies for mobile apps?
The primary mobile app monetization strategies are: paid downloads (one-time purchase), freemium (free with in-app purchases), subscriptions (recurring revenue for ongoing content or services), and advertising (display, interstitial, or rewarded ads via networks like AdMob). Subscriptions generate the highest lifetime value and are the model Apple and Google most actively promote through their storefronts. [Source: Google Play Console Help; Apple Developer]
What is the difference between in-app purchases and subscriptions on mobile?
In-app purchases (IAPs) are one-time transactions for specific content or features — such as unlocking a level or removing ads. Subscriptions are recurring payments (weekly, monthly, or annually) for continuous access to content or services. Both Apple's StoreKit and Google Play Billing Library support both types, but subscriptions offer developers predictable recurring revenue and typically higher retention. [Source: Apple Developer; Android Developers / Google]
What is Google AdMob and how do developers use it to monetize apps?
Google AdMob is a mobile advertising platform by Google that lets developers earn revenue by displaying ads — including banner, interstitial, rewarded, and native formats — within their iOS and Android apps. Developers integrate the AdMob SDK, create ad unit IDs in the AdMob console, and Google's network fills ads programmatically, paying developers based on impressions or clicks. [Source: Google AdMob / Google Developers]
What is the global market share split between iOS and Android?
Android holds approximately 72% of the global smartphone operating system market, while iOS holds around 27%, based on data from StatCounter. However, iOS dominates in higher-income markets like the United States, United Kingdom, Japan, and Australia, where its share often exceeds 50–55%. Developers targeting global audiences generally prioritize Android first; premium market apps often launch iOS first. [Source: StatCounter GlobalStats]
What accessibility standards must mobile apps follow?
Mobile apps must meet accessibility standards under laws like the Americans with Disabilities Act (ADA) and Section 508 in the US. Both Apple's Human Interface Guidelines and Google's Material Design specify WCAG 2.1 AA compliance as the baseline. Apple provides the Accessibility framework (VoiceOver, Dynamic Type), and Android offers TalkBack and accessibility APIs to help developers meet these requirements. [Source: U.S. Access Board; Apple Developer; Android Developers]