👀 Views: 195 💬 Answers: 1 📅 Created: 2025-10-17

iOS Web3 smart-contracts swift

Currently developing a wallet application for iOS that integrates with Ethereum smart contracts. I'm using the Web3.swift library to facilitate interactions with the blockchain. At this stage, I need to ensure that transactions are sent with the correct nonce value to avoid conflicts, especially since multiple transactions might be triggered in quick succession. After reviewing the Web3.swift documentation, I implemented a function to fetch the current nonce for the user's account: ```swift let web3 = Web3(rpcURL: "https://mainnet.infura.io/v3/YOUR_INFURA_KEY") let address = EthereumAddress("YOUR_WALLET_ADDRESS") func getNonce() async throws -> BigUInt { let nonce = try await web3.eth.getTransactionCount(address: address!, block: .pending) return nonce } ``` This approach works when the app is idle, but I noticed that if a user initiates several transactions rapidly, the nonce might not reflect the correct value, leading to "Nonce too low" errors. To tackle this, I implemented a mechanism to track the last sent nonce and increment it manually, ensuring that each subsequent transaction uses the appropriate value. The relevant part of the code looks like this: ```swift var lastNonce: BigUInt = 0 func sendTransaction(to recipient: EthereumAddress, amount: BigUInt) async throws { let currentNonce = try await getNonce() let transaction = EthereumTransaction(to: recipient, value: amount, nonce: lastNonce) let txHash = try await web3.eth.sendTransaction(transaction) lastNonce += 1 // increment for next transaction print("Transaction sent with hash: \(txHash)") } ``` However, I’m still facing issues where the lastNonce sometimes doesn’t match the blockchain’s expected nonce, especially after a failed transaction. Would implementing a retry mechanism for nonce fetching help? Also, are there any best practices around handling nonce management in a high-frequency transaction scenario that I might not be considering? Any insights or sample implementations would be greatly appreciated! Am I approaching this the right way?