WalletConnect Integration in Mobile Crypto App

WalletConnect Integration in Mobile Crypto Applications

WalletConnect is an open protocol for connecting mobile wallets with DApps. Users scan a QR code or follow a deep link to establish a secure, encrypted connection between their wallet and a web application without storing private keys on the DApp server.

WalletConnect v2: What Changed

WalletConnect v1 was deprecated in 2023. v2 (now called Web3Modal SDK / AppKit) uses a centralized relay server but maintains end-to-end cryptography. Key differences from v1:

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

iOS Implementation (Swift)

The official SDK is WalletConnectSwiftV2. Install via SPM:

// Package.swift or Xcode Package Manager
.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())

Handle incoming session proposals:

Sign.instance.sessionProposalPublisher
    .receive(on: DispatchQueue.main)
    .sink { [weak self] proposal in
        // Show user the requested methods and networks
        self?.showApprovalAlert(proposal: proposal)
    }
    .store(in: &cancellables)

On approval, create a namespace object with supported methods (eth_sendTransaction, personal_sign, eth_signTypedData) and call Sign.instance.approve(proposalId:namespaces:).

Handling Signature Requests

After session establishment, the DApp sends requests. The most common is personal_sign:

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] ?? ""
            // Show user what is being signed
            self?.showSignRequest(message: message, request: request)
        case "eth_sendTransaction":
            // Display transaction details
            break
        default:
            // Reject unknown methods
            Task { try await Sign.instance.respond(
                topic: request.topic,
                requestId: request.id,
                response: .error(.methodNotFound)
            )}
        }
    }
    .store(in: &cancellables)

Important: never sign automatically—every signature request requires explicit user confirmation.

Deep Links for Mobile Use

WalletConnect supports two modes: QR codes (for desktop DApps) and Universal Links / Custom URL Schemes (for mobile DApps). For wallet-to-wallet connections, users tap a button in the mobile browser DApp, which redirects them through a deep link with wc:// URI.

Handle URIs in SceneDelegate / @main App:

.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 through CoreClient.Wallet.setWalletDelegate(delegate).

Testing

WalletConnect provides a test DApp at lab.web3modal.com—a useful tool for testing all signature methods without a real blockchain. For transactions, use test networks (Sepolia, Mumbai).

Timeline: basic WalletConnect v2 integration with personal_sign and eth_sendTransaction—1–2 weeks. Full multi-chain support, eth_signTypedData v4, session revocation, and connection state UI—3–4 weeks.