Use Xcode to add to the project (File -> Swift Packages) or add this to your Package.swift
file:
.package(url: "https://github.com/argentlabs/web3.swift", from: "1.1.0")
Add web3.swift to your Podfile
:
pod 'web3.swift'
Then run the following command:
$ pod install
Create an instance of EthereumAccount
with a EthereumKeyStorage
provider. This provides a wrapper around your key for web3.swift to use. NOTE We recommend you implement your own KeyStorage provider, instead of relying on the provided EthereumKeyLocalStorage
class. This is provided as an example for conformity to the EthereumSingleKeyStorageProtocol
.
import web3
// This is just an example. EthereumKeyLocalStorage should not be used in production code
let keyStorage = EthereumKeyLocalStorage()
let account = try? EthereumAccount.create(replacing: keyStorage, keystorePassword: "MY_PASSWORD")
Create an instance of EthereumHttpClient
or EthereumWebSocketClient
. This will then provide you access to a set of functions for interacting with the Blockchain.
EthereumHttpClient
guard let clientUrl = URL(string: "https://an-infura-or-similar-url.com/123") else { return }
let client = EthereumHttpClient(url: clientUrl)
OR
EthereumWebSocketClient
guard let clientUrl = URL(string: "wss://sepolia.infura.io/ws/v3//123") else { return }
let client = EthereumWebSocketClient(url: clientUrl)
You can then interact with the client methods, such as to get the current gas price:
client.eth_gasPrice { (error, currentPrice) in
print("The current gas price is \(currentPrice)")
}
If using async/await
you can await
on the result
let gasPrice = try await client.eth_gasPrice()
Given a smart contract function ABI like ERC20 transfer
:
function transfer(address recipient, uint256 amount) public returns (bool)
then you can define an ABIFunction
with corresponding encodable Swift types like so:
public struct Transfer: ABIFunction {
public static let name = "transfer"
public let gasPrice: BigUInt? = nil
public let gasLimit: BigUInt? = nil
public var contract: EthereumAddress
public let from: EthereumAddress?
public let to: EthereumAddress
public let value: BigUInt
public init(contract: EthereumAddress,
from: EthereumAddress? = nil,
to: EthereumAddress,
value: BigUInt) {
self.contract = contract
self.from = from
self.to = to
self.value = value
}
public func encode(to encoder: ABIFunctionEncoder) throws {
try encoder.encode(to)
try encoder.encode(value)
}
}
This function can be used to generate contract call transactions to send with the client:
let function = transfer(contract: "0xtokenaddress", from: "0xfrom", to: "0xto", value: 100)
let transaction = try function.transaction()
client.eth_sendRawTransaction(transaction, withAccount: account) { (error, txHash) in
print("TX Hash: \(txHash)")
}
If using async/await
you can await
on the result
let txHash = try await client.eth_sendRawTransaction(transaction, withAccount: account)
Currently we don't support code generation as making it properly is a bigger project, and should possibly live outside of this repository.
You can try this project instead: imanrep/swiftabigen
The library provides some types and helpers to make interacting with web3 and Ethereum easier.
EthereumAddress
: For representation of addresses, including checksum support.BigInt
and BigUInt
: Using BigInt libraryEthereumBlock
: Represents the block, either number of RPC-specific definitions like 'Earliest' or 'Latest'EthereumTransaction
: Wraps a transaction. Encoders and decoders can work with it to generate proper data
fields.All extensions are namespaced under 'Int
to a hex string:
let gwei = 100
let hexgwei = gwei.web3.hexString
Supported conversions:
Data
Int
BigUInt
String
, Int
, BigUInt
, Data
to a hex byte string ("0xabc")String
We support querying ERC20 token data via the ERC20
struct. Calls allow to:
Transfer
eventsWe support querying ERC721 token data via the ERC721
struct. Including:
Transfer
eventsWe also include additional helpers to interact with ZKSync Era, by importing web3_zksync
.
Take a look at ZKSyncTransaction or use directly
ZKSyncClient which has similar API as the EthereumClient
Some of the tests require a private key, which is not stored in the repository. You can ignore these while testing locally, as CI will use the encrypted secret key from Github.
It's better to run only the tests you need, instead of the whole test suite while developing. If you ever need to set up the key locally, take a look at TestConfig.swift
where you can manually set it up. Alternatively you can set it up by calling the script setupKey.sh
and passing the value (adding 0x) so it's written to an ignored file.
We built web3.swift to be as lightweight as possible. However, given the cryptographic nature of Ethereum, there's a couple of reliable C libraries you will find packaged with this framework:
Package dependencies:
Also for Linux build, we can't use Apple crypto APIs, so we embedded a small subset of CryptoSwift (instead of importing the whole library). Credit to Marcin Krzyżanowski
The initial project was crafted by the team at Argent. However, we encourage anyone to help implement new features and to keep this library up-to-date. For features and fixes, simply submit a pull request to the develop branch. Please follow the contributing guidelines.
For bug reports and feature requests, please open an issue.
Released under the MIT license.