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 installCreate 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.BigIntandBigUInt: 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 properdatafields.
All extensions are namespaced under ''.web3. So for example, to convert an Int to a hex string:
let gwei = 100
let hexgwei = gwei.web3.hexStringSupported conversions:
- Convert from hex byte string ("0xabc") to
Data - Convert from hex byte string ("0xabc") to
Int - Convert from hex byte string ("0xabc") to
BigUInt - Convert
String,Int,BigUInt,Datato a hex byte string ("0xabc") - Add or remove hex prefixes when working with
String
We support querying ERC20 token data via the ERC20 struct. Calls allow to:
- Get the token symbol, name, and decimals
- Get a token balance
- Retrieve
Transferevents
We support querying ERC721 token data via the ERC721 struct. Including:
- Get the token symbol, name, and decimals
- Get a token balance
- Retrieve
Transferevents - Decode standard JSON for NFT metadata. Please be aware some smart contracts are not 100% compliant with standard.
We 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:
- keccac-tiny: An implementation of the FIPS-202-defined SHA-3 and SHAKE functions in 120 cloc (156 lines).
- Tiny AES: A small and portable implementation of the AES ECB, CTR and CBC encryption algorithms.
- secp256k1.swift
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.
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