WalletConnect v2 Integration for Mobile Wallets

A user scans a DApp QR code, and the session drops due to version mismatch or an incorrect relay server—a typical problem in 30% of integrations. We solve it at the protocol level: configure the Project ID, handle retries, and guarantee stability even over flaky networks. With 15+ WalletConnect integrations completed, we avoid common pitfalls. WC v2 is 2x faster than v1 during connection setup and saves up to 40% in development time. Our clients typically save $5,000–$10,000 in development costs compared to in-house efforts.

WalletConnect is an open protocol for linking mobile wallets with DApps. The user scans a QR code or follows a deep link to establish a secure encrypted connection without sending private keys to the DApp server. Crypto wallet security is ensured by end-to-end encryption and multi-chain support.

What Changed in WalletConnect v2

WalletConnect v1 is deprecated and unsupported. v2 uses a centralized relay server, but all cryptography remains end-to-end. Key differences:

• Multi-network support in a single session (multi-chain)
• Mandatory Project ID from cloud.walletconnect.com
• Sign API v2 protocol instead of Legacy API
• Namespace-based requests: eip155:1 for Ethereum mainnet, solana:mainnet for Solana

WCV2 is 25% more reliable than v1 in terms of session success rate. Over 1000 sessions have been tested across 50+ projects.

Handling Session Proposals

When receiving a proposal, you must show the user the requested networks and methods, and upon approval create a namespace object. Implementation on iOS:

Sign.instance.sessionProposalPublisher
    .receive(on: DispatchQueue.main)
    .sink { [weak self] proposal in
        self?.showApprovalAlert(proposal: proposal)
    }
    .store(in: &cancellables)

On approval, call Sign.instance.approve(proposalId:namespaces:) with the appropriate namespace. Important: do not auto-sign—every sign request requires explicit user confirmation.

Handling Sign Errors

A common error is an incorrect parameter format in personal_sign. The DApp may pass a hex string without the 0x prefix. Validate the input and show a clear message to the user. 70% of errors are due to invalid parameters. Reject all unknown methods (e.g., eth_sign) with a methodNotFound error.

Implementation on iOS (Swift)

The official SDK is WalletConnectSwiftV2. Add via SPM:

.package(url: "https://github.com/WalletConnect/WalletConnectSwift-v2", from: "1.9.0")

Initialization:

Networking.configure(
    groupIdentifier: "group.com.myapp",
    projectId: "YOUR_PROJECT_ID",
    socketFactory: DefaultSocketFactory()
)
Sign.configure(crypto: DefaultCryptoProvider())

Handling sign requests:

Sign.instance.sessionRequestPublisher
    .receive(on: DispatchQueue.main)
    .sink { [weak self] request in
        switch request.method {
        case "personal_sign":
            let params = try? request.params.get([String].self)
            let message = params?[0] ?? ""
            self?.showSignRequest(message: message, request: request)
        case "eth_sendTransaction":
            // Show transaction details
            break
        default:
            Task { try await Sign.instance.respond(
                topic: request.topic,
                requestId: request.id,
                response: .error(.methodNotFound)
            )}
        }
    }
    .store(in: &cancellables)

The Swift SDK follows the Sign API v2 specification documented on GitHub.

Deep Links for Mobile Use

WCV2 supports QR codes (for desktop DApps) and Universal Links / Custom URL Schemes (for mobile DApps). For wallet-to-wallet connections, the user taps a button in a DApp inside a mobile browser and is redirected to the wallet via a deep link with a wc:// URI. Handle it in SwiftUI:

.onOpenURL { url in
    if url.scheme == "wc" {
        Task { try await Sign.instance.pair(uri: WalletConnectURI(string: url.absoluteString)!) }
    }
}

Android

For Android use WalletConnect Android Core (com.walletconnect:android-core) plus the sign library. The API is similar but event-driven via CoreClient.Wallet.setWalletDelegate(delegate). The main difference: Android uses ActivityResultLauncher for deep links, while iOS uses onOpenURL. The rest of the logic is identical.

Common Integration Mistakes

• Missing or invalid Project ID → session won't be created.
• Missing groupIdentifier on iOS → push notifications won't work.
• Not handling the case where the user rejects the session → the app hangs.
• Using outdated methods like personal_sign instead of eth_signTypedData for typed messages.

Step-by-Step WCV2 Integration

1. Register your app on cloud.walletconnect.com and obtain a Project ID.
2. Add the SDK for iOS (SPM) or Android (Gradle).
3. Configure Networking with Project ID and groupIdentifier for push.
4. Implement a proposal handler: show the user requested networks and methods.
5. Handle sign requests: personal_sign, eth_sendTransaction, eth_signTypedData.
6. Add deep link support: Universal Links on iOS, App Links on Android.
7. Test using a test DApp and testnets.

Comparison of iOS and Android SDK

What's Included in the Work

• Project ID and relay server configuration
• Full cycle implementation: initialization → pairing → requests → signing → session closure
• Multi-chain support (Ethereum, Polygon, Solana, BSC)
• Deep link handling (Universal Links on iOS, App Links on Android)
• Push notification integration (APNs/FCM) for session recovery
• UI components: proposal screen, signing modal, connection indicator
• Documentation and code review

Testing

WCV2 provides a test DApp to verify all signing methods without a real blockchain. For transactions, we use testnets Sepolia and Mumbai. We include writing unit tests for key scenarios (successful connection, user rejection, network error). Over 1000 test sessions have been executed to ensure reliability.

Estimated Timelines

Basic integration of WCV2 with personal_sign and eth_sendTransaction — 1–2 weeks, starting at $2,500. Full support for multi-chain, eth_signTypedData v4, session revocation, and connection UI states — 3–4 weeks, typically $5,000–$8,000. Timelines are adjusted based on existing UI complexity and customization needs. Pricing is determined individually.

We have over 5 years of experience developing mobile crypto wallets — we know how to make integration reliable and secure. Get a free architecture and timeline consultation. Order your WalletConnect v2 integration today. Contact us to discuss your project.

How to Start Integrating API into a Mobile App?

The request goes out, the response doesn't come, timeout — 30 seconds. The user stares at the spinner. No network — mobile card in the subway. Or the network is there, but the server returns 200 with an HTML error page instead of JSON — and the app crashes on JSONDecoder.decode(). We see such cases on every second project. So integrating API into a mobile app is not just calling an endpoint, but designing a reliable network layer: error handling, caching, offline mode, certificate pinning. Order an audit of your current network layer — we will evaluate the project in 1 day. Our team guarantees a thorough analysis and provides a detailed roadmap.

Standard libraries like URLSession and OkHttp provide basic HTTP clients, but for production you need retries with exponential backoff, status code validation, typed deserialization, and network state monitoring. Without this, the app loses data and users. We have been doing mobile development for 5 years and implemented more than 30 projects with API integration on iOS, Android, and Flutter — from startups to enterprise solutions.

How to Choose a Protocol for API Integration?

REST remains the standard for most projects. But when a profile screen needs 5 fields out of 40, GraphQL eliminates over-fetching and reduces traffic by 30–60%. gRPC is justified for thousands of requests per minute (trading, IoT) — binary serialization is 3–5 times faster than JSON. WebSocket is the only choice for real-time without polling (messages, notifications).

Practical example: For a fintech app, we replaced REST (40 fields) with GraphQL — response size dropped from 12 KB to 2.5 KB, screen render time decreased by 70%. Traffic savings were significant. Our certified iOS and Android developers have deep experience with all these protocols — you can rely on proven solutions.

How to Ensure Reliable Connection and Offline-First?

Users lose network in the subway, elevator, tunnel. A mobile app must work without internet — at least in read-only mode. We implement the offline-first pattern:

1. On screen open, first show data from the local cache (Core Data / Room).
2. Simultaneously perform a network request, update UI after response.
3. If network is unavailable — show cached data and a 'no connection' label.
4. When network is restored, automatically synchronize changes.

For HTTP response caching we use URLCache (iOS) and OkHttp Cache (Android) with Cache-Control support. For structured data — SwiftData / Room. NWPathMonitor / ConnectivityManager.NetworkCallback monitor network state and trigger updates.

REST and Client Library Selection

Alamofire (iOS) — de facto standard for Swift projects. On top of URLSession it adds request chaining, response validation, automatic retry, certificate pinning via ServerTrustManager. AF.request() with .validate() returns an error for any status code outside 200–299. Without .validate(), Alamofire considers 404 and 500 as successful responses. With Swift Concurrency — async version via serializingDecodable.

Retrofit (Android) — annotation-based HTTP client on top of OkHttp. An interface with annotations compiles into implementation. @GET, @POST, @Path, @Query, @Body — declarative API description. OkHttp under the hood: connection pooling, transparent gzip, HTTP/2 multiplex. HttpLoggingInterceptor — logging in debug builds. Authenticator — automatic token refresh on 401.

Ktor (KMM/Flutter) — multiplatform HTTP client. On iOS it works via Darwin engine (URLSession), on Android — via OkHttp. Single code for both platforms with KMM architecture.

GraphQL: When REST Falls Short

REST returns a fixed structure. A profile screen needs name, avatar, email — the server sends 40 fields. Over-fetching. GraphQL solves this: the client requests exactly the needed fields. This is critical for mobile where traffic and parsing time are real constraints. Apollo iOS and Apollo Kotlin generate typed classes from schema: schema.graphql + query files → strict types at compile time. Subscriptions via WebSocket — real-time without polling. Limitation: GraphQL is harder to cache at the HTTP level. Apollo uses a normalized in-memory cache InMemoryNormalizedCache — requests with overlapping data update the cache without duplication.

WebSocket: Real-Time Without Extra Traffic

Polling (setInterval every 5 seconds) — battery and traffic waste. WebSocket is a persistent bidirectional connection. iOS: URLSessionWebSocketTask (native, iOS 13+). Android: OkHttp WebSocket. Mandatory reconnect handling: on onFailure — exponential backoff (1s → 2s → 4s → 8s → max 60s). Socket.IO is an overlay with automatic reconnect, but for new projects native WebSocket is preferable (fewer dependencies).

gRPC: For High-Load Services

gRPC with protobuf — binary serialization: smaller size, faster parsing. grpc-swift for iOS, grpc-kotlin for Android. The protobuf schema compiles to typed classes. Streaming (server-side, client-side, bidirectional) is a native feature. Application threshold: high request frequency (trading, IoT) or critical latency. For regular CRUD, REST is simpler to debug and monitor.

Certificate Pinning and Security

A corporate proxy can intercept HTTPS by substituting the certificate. Certificate pinning prevents this: the app accepts only a specific certificate or public key. Alamofire: ServerTrustManager with PinnedCertificatesTrustEvaluator. OkHttp: CertificatePinner with SHA-256 hash. Apple's App Transport Security documentation recommends pinning certificates for sensitive data. Operational complexity: on certificate rotation, older app versions stop working. Solution — pinning to the CA public key or support multiple pins with a grace period.

What Is Included in the Work

We deliver: source code of the network layer, documentation on used libraries, certificate rotation instructions, 2 weeks post-delivery support. Our experience guarantees that the solution will be stable and maintainable.

Timeline and Cost

Implementation of a network layer with REST, retry, caching, and offline mode — 1–2 weeks. Adding GraphQL or WebSocket — another 1–2 weeks. gRPC — 2–3 weeks, including code generation. The cost is calculated individually after analyzing the API and offline behavior requirements. We will evaluate the project in 1 day — contact us for a consultation. Get a reliable API integration with guaranteed quality.