Integrating Sentry for mobile application error tracking

Integrating Sentry for mobile app error tracking

Sentry differs from Firebase Crashlytics in one key way — it tracks not just crashes, but performance: transactions, spans, slow HTTP requests, ANR/hang on UI thread. For applications where not just crashes matter but UX degradation, this makes Sentry more informative.

iOS: SPM connection

Add https://github.com/getsentry/sentry-cocoa to Package Dependencies, then in AppDelegate or @main:

import Sentry

SentrySDK.start { options in
    options.dsn = "https://<key>@sentry.io/<project>"
    options.environment = Bundle.main.object(forInfoDictionaryKey: "SentryEnvironment") as? String ?? "production"
    options.tracesSampleRate = 0.2  // 20% of transactions for performance
    options.profilesSampleRate = 0.1
    options.attachViewHierarchy = true  // view hierarchy snapshot on crash
}

attachViewHierarchy = true — useful feature: each crash report includes UIView/SwiftUI hierarchy tree at moment of crash. Immediately see which screen and UI state the crash occurred in.

Android: Gradle + Application

implementation("io.sentry:sentry-android:7.+")

// Application.onCreate()
SentryAndroid.init(this) { options ->
    options.dsn = "https://<key>@sentry.io/<project>"
    options.environment = BuildConfig.SENTRY_ENVIRONMENT
    options.tracesSampleRate = 0.2
    options.isEnableUserInteractionTracing = true  // auto-trace taps
}

isEnableUserInteractionTracing automatically creates transactions on user UI interaction. Without additional code see that "Checkout" button triggers 4.2-second network request on 3G.

Performance monitoring

// iOS: manual transaction
let transaction = SentrySDK.startTransaction(name: "checkout", operation: "ui.action")
let span = transaction.startChild(operation: "http.client", description: "POST /orders")
// ... request ...
span.finish()
transaction.finish()

Transactions appear in Performance section in Sentry. Shows p50/p75/p95/p99 percentiles, heatmap of slow requests and exact spans.

Custom tags and breadcrumbs

SentrySDK.configureScope { scope in
    scope.setUser(SentryUser(userId: userId))
    scope.setTag(value: "premium", key: "subscription")
    scope.addBreadcrumb({
        let crumb = Breadcrumb()
        crumb.message = "Opened shopping cart screen"
        crumb.category = "navigation"
        return crumb
    }())
}

Breadcrumbs — sequence of events before crash. Allow reconstructing user path without reproducing bug.

Source maps for React Native

If project is React Native — need to upload JS bundle source maps on each release:

npx sentry-cli releases \
  files "$VERSION" \
  upload-sourcemaps \
  --dist "$BUILD_NUMBER" \
  ./dist/bundle.js.map

Without source maps, RN crash stack trace looks like set of anonymous functions from minified bundle.

What's included in the work

• Connecting sentry-cocoa / sentry-android / sentry-react-native
• Configuring environments (dev / staging / production)
• Performance tracing configuration with reasonable sample rate
• Scope integration: User ID, tags, breadcrumbs
• Configuring alerts on error rate and p95 latency
• Upload dSYM / ProGuard mapping / JS source maps in CI

Timeline

Basic crash reporting integration: 0.5–1 day. Full performance tracing with custom transactions: 1–2 days. Cost calculated individually.