LicenseApache License 2.0
Platformsios 9.0, osx 10.11
DependenciesAlamofire, Alamofire-Synchronous, BigInt, Result, CryptoSwift, libsodium, secp256k1_ios, PromiseKit


web3swiftAsk questions

Important notices

With the version 0.3.0 API should be less volatile. All public functions should return a Result instead of nil or throwing.

Example is updated for 0.5.0, although please prefer to use tests as an example for your code.


  • Swift implementation of web3.js functionality :zap:
  • Interaction with remote node via JSON RPC :thought_balloon:
  • Smart-contract ABI parsing :book:
    • ABI deconding (V2 is supported with return of structures from public functions. Part of 0.4.22 Solidity compiler)
    • RLP encoding
  • Interactions (read/write to Smart contracts) :arrows_counterclockwise:
  • Local keystore management (geth compatible)
  • Literally following the standarts:
    • BIP32 HD Wallets: Deterministic Wallet
    • BIP39 (Seed phrases)
    • BIP44 (Key generation prefixes)
    • EIP-155 (Replay attacks protection) enforced!

Check this out

  • Private key and transaction were created directly on the iOS device and sent directly to Infura node
  • Native API
  • Security (as cool as hard wallet! Right out-of-the-box! :box: )
  • No unnecessary dependencies
  • Possibility to work with all existing smart contracts
  • Referencing the newest features introduced in Solidity

Design decisions

  • Not every JSON RPC function is exposed yet, priority is gives to ones required for mobile devices
  • Functionality was focused on serializing and signing transactions locally on device to send raw transaction to Ethereum network
  • Requirements for password input on every transactions are indeed a design decision. Interface designers can save user passwords given user’s consent
  • Public function for private key export is exposed for user convenience, but marked as UNSAFE_ :) Normal workflow takes care of EIP155 compatibility and proper clearing of private key data from memory

Here it is

Nonce: 35
Gas price: 5000000000
Gas limit: 21000
To: 0x6394b37Cf80A7358b38068f0CA4760ad49983a1B
Value: 1000000000000000
Data: 0x
v: 43
r: 73059897783840535708732471549376620878882680550447969052675399628060606060727
s: 12280625377431973240236065453692843538037349746280474092545114784968542260859
Intrinsic chainID: Optional(4)
Infered chainID: Optional(4)
sender: Optional(web3swift.EthereumAddress(_address: "0x855adf524273c14b7260a188af0ae30e82e91959"))

["id": 1514485925, "result": 0xc6eca60ecac004a1501a4323a10edb7fa4cd1a0896675f6b51704c84dedad056, "jsonrpc": 2.0]
On Rinkeby TXid = 0xc6eca60ecac004a1501a4323a10edb7fa4cd1a0896675f6b51704c84dedad056


You can try it by yourself by running the example project:

  • Clone the repo
  • cd Example/web3swiftExample
  • run pod install from the Example/web3swiftExample directory.
  • open ./web3swiftExample.xcworkspace


Web3swift requires Swift 4.1 and iOS 9.0 or macOS 10.13 although we recommend to use the latest iOS and MacOS versions for your own safety. Don’t forget to set iOS version in a Podfile, otherwise you get an error if deployment target is less than the latest SDK.




CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:

$ sudo gem install cocoapods

To integrate web3swift into your Xcode project using CocoaPods, specify it in your Podfile:

source ''
platform :ios, '9.0'

target '<Your Target Name>' do
    pod 'web3swift', '~> 0.8.0'

Then, run the following command:

$ pod install


  • [x] Create Account
  • [x] Import Account
  • [x] Sign transictions
  • [x] Send transactions, call functions of smart-contracts, estimate gas costs
  • [x] Serialize and deserialize transactions and results to native Swift types
  • [x] Convenience functions for chain state: block number, gas price
  • [x] Check transaction results and get receipt
  • [x] Parse event logs for transaction
  • [x] Manage user’s private keys through encrypted keystore abstractions
  • [x] Batched requests in concurrent mode, checks balances of 580 tokens (from the latest MyEtherWallet repo) over 3 seconds


Here you can see a few examples of use of our library

Initializing Ethereum address

let coldWalletAddress = EthereumAddress("0x6394b37Cf80A7358b38068f0CA4760ad49983a1B")
let constractAddress = EthereumAddress("0x45245bc59219eeaaf6cd3f382e078a461ff9de7b")

Ethereum addresses are checksum checked if they are not lowercased and always length checked

Setting options

var options = Web3Options.defaultOptions()
    // public var to: EthereumAddress? = nil - to what address transaction is aimed
    // public var from: EthereumAddress? = nil - form what address it should be sent (either signed locally or on the node)
    // public var gasLimit: BigUInt? = BigUInt(90000) - default gas limit
    // public var gasPrice: BigUInt? = BigUInt(5000000000) - default gas price, quite small
    // public var value: BigUInt? = BigUInt(0) - amount of WEI sent along the transaction
options.gasPrice = gasPrice
options.gasLimit = gasLimit
options.from = EthereumAddress("0xE6877A4d8806e9A9F12eB2e8561EA6c1db19978d")

Getting ETH balance

let address = EthereumAddress("0xE6877A4d8806e9A9F12eB2e8561EA6c1db19978d")!
let web3Main = Web3.InfuraMainnetWeb3()
let balanceResult = web3Main.eth.getBalance(address)
guard case .success(let balance) = balanceResult else {return}

Getting gas price

let web3Main = Web3.InfuraMainnetWeb3()
let gasPriceResult = web3Main.eth.getGasPrice()
guard case .success(let gasPrice) = gasPriceResult else {return}

Getting ERC20 token balance

let contractAddress = EthereumAddress("0x45245bc59219eeaaf6cd3f382e078a461ff9de7b")! // BKX token on Ethereum mainnet
let contract = web3.contract(Web3.Utils.erc20ABI, at: contractAddress, abiVersion: 2)! // utilize precompiled ERC20 ABI for your concenience
guard let bkxBalanceResult = contract.method("balanceOf", parameters: [coldWalletAddress] as [AnyObject], options: options)?.call(options: nil) else {return} // encode parameters for transaction
guard case .success(let bkxBalance) = bkxBalanceResult, let bal = bkxBalance["0"] as? BigUInt else {return} // bkxBalance is [String: Any], and parameters are enumerated as "0", "1", etc in order of being returned. If returned parameter has a name in ABI, it is also duplicated
print("BKX token balance = " + String(bal))

Sending ETH

let web3Rinkeby = Web3.InfuraRinkebyWeb3()
web3Rinkeby.addKeystoreManager(bip32keystoreManager) // attach a keystore if you want to sign locally. Otherwise unsigned request will be sent to remote node
options.from = bip32ks?.addresses?.first! // specify from what address you want to send it
intermediateSend = web3Rinkeby.contract(Web3.Utils.coldWalletABI, at: coldWalletAddress, abiVersion: 2)!.method(options: options)! // an address with a private key attached in not different from any other address, just has very simple ABI
let sendResultBip32 = intermediateSend.send(password: "BANKEXFOUNDATION")

Sending ERC20

var convenienceTransferOptions = Web3Options.defaultOptions()
convenienceTransferOptions.gasPrice = gasPriceRinkeby
let convenienceTokenTransfer = web3Rinkeby.eth.sendERC20tokensWithNaturalUnits(tokenAddress: EthereumAddress("0xa407dd0cbc9f9d20cdbd557686625e586c85b20a")!, from: (ks?.addresses?.first!)!, to: EthereumAddress("0x6394b37Cf80A7358b38068f0CA4760ad49983a1B")!, amount: "0.0001", options: convenienceTransferOptions) // there are also convenience functions to send ETH and ERC20 under the .eth structure
let gasEstimateResult = convenienceTokenTransfer!.estimateGas(options: nil)
guard case .success(let gasEstimate) = gasEstimateResult else {return}
convenienceTransferOptions.gasLimit = gasEstimate
let convenienceTransferResult = convenienceTokenTransfer!.send(password: "BANKEXFOUNDATION", options: convenienceTransferOptions)
switch convenienceTransferResult {
    case .success(let res):
        print("Token transfer successful")
    case .failure(let error):

Global plans

  • Full reference web3js functionality
  • Light Ethereum subprotocol (LES) integration

Apps using this library

If you’ve used this project in a live app, please let us know!

If you are using web3swift in your app or know of an app that uses it, please add it to this list.

Special thanks to

  • Gnosis team and their library Bivrost-swift for inspiration for the ABI decoding approach
  • Trust iOS Wallet for collaboration and discussion for initial idea
  • Official Ethereum and Solidity docs, everything was written from ground truth standards


For the latest version, please check develop branch.
Changes from this branch will be merged into the master branch at some point.


When using this pod references to this repo, BANKEX and BANKEX Foundation are appreciated.


Alex Vlasov, @shamatar, [email protected]

Petr Korolev, @skywinder, [email protected]


web3swift is available under the Apache License 2.0 license. See the LICENSE file for more info.

Latest podspec

    "name": "web3swift",
    "version": "0.9.0",
    "summary": "Web3 implementation in vanilla Swift for iOS ans macOS",
    "description": "Web3 implementation in vanilla Swift, intended for mobile developers of wallets, Dapps and Web3.0",
    "homepage": "",
    "license": "Apache License 2.0",
    "authors": {
        "Alex Vlasov": "[email protected]"
    "source": {
        "git": "",
        "tag": "0.9.0"
    "social_media_url": "",
    "swift_version": "4.1",
    "module_name": "web3swift",
    "platforms": {
        "ios": "9.0",
        "osx": "10.11"
    "public_header_files": "web3swift/**/*.{h}",
    "source_files": [
    "pod_target_xcconfig": {
    "frameworks": "CoreImage",
    "dependencies": {
        "Alamofire": [
            "~> 4.7"
        "Alamofire-Synchronous": [
            "~> 4.0"
        "BigInt": [
            "~> 3.0.1"
        "Result": [
            "~> 3.0.0"
        "CryptoSwift": [
            "~> 0.10.0"
        "libsodium": [
            "~> 1.0.12"
        "secp256k1_ios": [
            "~> 0.1.3"
        "PromiseKit": [
            "~> 6.3.0"

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