Web3 is available through CocoaPods. To install
it, simply add the following line to your Podfile:
pod 'Web3Swift.io'To send some wei from an account with a private key 0x1636e10756e62baabddd4364010444205f1216bdb1644ff8f776f6e2982aa9f5 to an account with an address 0x79d2c50Ba0cA4a2C6F8D65eBa1358bEfc1cFD403 on a mainnet:
import Web3Swift
let sender: PrivateKey = EthPrivateKey(
hex: "0x1636e10756e62baabddd4364010444205f1216bdb1644ff8f776f6e2982aa9f5"
)
let recipient: BytesScalar = EthAddress(
hex: "0x79d2c50Ba0cA4a2C6F8D65eBa1358bEfc1cFD403"
)
let network: Network = InfuraNetwork(
chain: "mainnet",
apiKey: "0c4d6dc730244b4185a6bde26f981bff"
)
let amount: BytesScalar = EthNumber(
hex: "0xde0b6b3a7640000" // 10^18 in hex that represents 1 ETH
)
let response = try SendRawTransactionProcedure(
network: network,
transactionBytes: EthDirectTransactionBytes(
network: network,
senderKey: sender,
recipientAddress: recipient,
weiAmount: amount
)
).call()
//If Ethereum network accepts the transaction, you could get transaction hash from the response. Otherwise, library will throw `DescribedError`
print(response["result"].string ?? "Something went wrong")If you want to specify gas price or gas amount take a look at EthDirectTransactionBytes.swift.
To send ether instead of wei:
let ethAmount = 1.1
try SendRawTransactionProcedure(
...,
weiAmount: EthToWei(
amount: ethAmount
)
).call()To send some ERC-20 tokens, for example OmiseGO, we need to get the smart contract address.
OMG tokens are managed by smart contract at 0xd26114cd6EE289AccF82350c8d8487fedB8A0C07.
In this example we send token from an account with a private key 0x1636e10756e62baabddd4364010444205f1216bdb1644ff8f776f6e2982aa9f5 to an account with an address 0x79d2c50Ba0cA4a2C6F8D65eBa1358bEfc1cFD403 on a mainnet:
import Web3Swift
let network: Network = InfuraNetwork(
chain: "mainnet", apiKey: "0c4d6dc730244b4185a6bde26f981bff"
)
let sender: PrivateKey = EthPrivateKey(
hex: "0x1636e10756e62baabddd4364010444205f1216bdb1644ff8f776f6e2982aa9f5"
)
let recipient: BytesScalar = EthAddress(
hex: "0x79d2c50Ba0cA4a2C6F8D65eBa1358bEfc1cFD403"
)
let token: BytesScalar = EthAddress(
hex: "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07"
)
let amount: BytesScalar = EthNumber(
hex: "0xde0b6b3a7640000" // 10^18 in hex that represents 1 OMG token
)
let response = try SendRawTransactionProcedure(
network: network,
transactionBytes: EthContractCallBytes(
network: network,
senderKey: sender,
contractAddress: token,
weiAmount: EthNumber(
hex: "0x00" //We do not need to provide ethers to not payable functions.
),
functionCall: EncodedABIFunction(
signature: SimpleString(
string: "transfer(address,uint256)"
),
parameters: [
ABIAddress(
address: recipient
),
ABIUnsignedNumber(
origin: amount
)
]
)
)
).call()
//If Ethereum network accepts the transaction, you could get transaction hash from the response. Otherwise, library will throw `DescribedError`
print(response["result"].string ?? "Something went wrong")You can swiftly deal with other ERC-20 functions just by encoding another EncodedABIFunction .
Here is an example of encoding transferFrom(from,to,value) function
EncodedABIFunction(
signature: SimpleString(
string: "transferFrom(address,address,uint256)"
),
parameters: [
ABIAddress(
address: EthAddress(
hex: "0xFBb1b73C4f0BDa4f67dcA266ce6Ef42f520fBB98"
)
),
ABIAddress(
address: EthAddress(
hex: "0x79d2c50Ba0cA4a2C6F8D65eBa1358bEfc1cFD403"
)
),
ABIUnsignedNumber(
origin: EthNumber(
hex: "0x01"
)
)
]
)More encoding example including advanced ones are placed at Example/Tests/ABI
You do not need to send transaction for reading data from a smart contract. Here is an example of checking address balance by making a call to smart contract function balanceOf(owner).
let balance = try HexAsDecimalString(
hex: EthContractCall(
network: InfuraNetwork(
chain: "mainnet", apiKey: "0c4d6dc730244b4185a6bde26f981bff"
),
contractAddress: EthAddress(
hex: "0xd26114cd6EE289AccF82350c8d8487fedB8A0C07" //OmiseGO token contract
),
functionCall: EncodedABIFunction(
signature: SimpleString(
string: "balanceOf(address)"
),
parameters: [
ABIAddress(
address: EthAddress(
hex: "0xFBb1b73C4f0BDa4f67dcA266ce6Ef42f520fBB98" //Bittrex
)
)
]
)
)
).value()
print(balance) // 13098857909137917398909558 is 13 098 857.909137917398909558 OMG tokensimport CryptoSwift
// Add your private key
let privateKey = EthPrivateKey(
hex: "YOUR_PRIVATE_KEY"
)
// Form the bytes for your message
// In our example we sign null Ethereum address
let messageBytes = try! EthAddress(
hex: "0x0000000000000000000000000000000000000000"
).value().bytes
// Create a message
// Don't forget that some services may expect
// a message with Ethereum prefix as here
let message = ConcatenatedBytes(
bytes: [
//Ethereum prefix
UTF8StringBytes(
string: SimpleString(
string: "\u{19}Ethereum Signed Message:\n32"
)
),
//message
Keccak256Bytes(
origin: SimpleBytes(
bytes:
)
)
]
)
// Use your custom hash function if needed
let hashFunction = SHA3(variant: .keccak256).calculate
// Create the signature
// Calculations are performed in a lazy way
// so you don't have to worry about performance
let signature = SECP256k1Signature(
privateKey: privateKey,
message: message,
hashFunction: hashFunction
)
// Now you can retrieve all the parameters
// of the signature or use it for the signing with web3
let r = PrefixedHexString(
bytes: try! signature.r()
)
let s = PrefixedHexString(
bytes: try! signature.s()
)
let v = try! signature.recoverID().value() + 27Getting results of the recent or previous transaction is one of the most common tasks during developing interactions with DApps. There are two JSON-RPC methods for getting basic and additional transaction info. The first one is eth_getTransactionByHash (example) and the second one is eth_getTransactionReceipt(example). You could use next library example to get needed information from the Ethereum blockchain.
import Web3Swift
import SwiftyJSON
let transactionHash = BytesFromHexString(
hex: "0x5798fbc45e3b63832abc4984b0f3574a13545f415dd672cd8540cd71f735db56"
)
let network = InfuraNetwork(
chain: "mainnet",
apiKey: "0c4d6dc730244b4185a6bde26f981bff"
)
let basicInfo: JSON = try TransactionProcedure(
network: network,
transactionHash: transactionHash
).call()
let advancedInfo: JSON = try TransactionReceiptProcedure(
network: network,
transactionHash: transactionHash
).call()
print(basicInfo["result"].dictionary ?? "Something went wrong")
/**
[
"blockNumber": 0x196666,
"value": 0x0,
"v": 0x1b,
"input":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,
"hash": 0x5798fbc45e3b63832abc4984b0f3574a13545f415dd672cd8540cd71f735db56,
"to": 0xbb9bc244d798123fde783fcc1c72d3bb8c189413,
"transactionIndex": 0x7,
"gasPrice": 0x4a817c800,
"r": 0xd92d67e4a982c45c78c1260fc2f644ed78483e2bf7d6151aab9ea40a8e172472,
"nonce": 0x0,
"blockHash": 0x1f716531f40858da4d4b08269f571f9f22c7b8bd921764e8bdf9cb2e0508efa1,
"from": 0xb656b2a9c3b2416437a811e07466ca712f5a5b5a,
"s": 0x6ee7e259e4f13378cf167bb980659520a7e5897643a2642586f246c6de5367d6,
"gas": 0x4c449
]
*/
print(advancedInfo["result"].dictionary ?? "Something went wrong")
/**
[
"root": 0xee69c77c73cd53b90e928e786b1c7f5b743a36dccd877128cf1dce7b46980a97,
"blockNumber": 0x196666,
"transactionIndex": 0x7,
"transactionHash": 0x5798fbc45e3b63832abc4984b0f3574a13545f415dd672cd8540cd71f735db56,
"blockHash": 0x1f716531f40858da4d4b08269f571f9f22c7b8bd921764e8bdf9cb2e0508efa1,
"from": 0xb656b2a9c3b2416437a811e07466ca712f5a5b5a,
"contractAddress": null,
"logsBloom": 0x00000000000000020000000000020000000000000000000000000000000000000000000000000000000000000000000000000000000000800000000000080000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000020000000000000000000200000000000000000000800000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000000000000,
"to": 0xbb9bc244d798123fde783fcc1c72d3bb8c189413,
"logs": [
{
"blockNumber" : "0x196666",
"topics" : [
"0x5790de2c279e58269b93b12828f56fd5f2bc8ad15e61ce08572585c81a38756f",
"0x000000000000000000000000000000000000000000000000000000000000003b"
],
"data" : "0x000000000000000000000000b656b2a9c3b2416437a811e07466ca712f5a5b5a00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000008000000000000000000000000000000000000000000000000000000000000000116c6f6e656c792c20736f206c6f6e656c79000000000000000000000000000000",
"logIndex" : "0x5",
"transactionHash" : "0x5798fbc45e3b63832abc4984b0f3574a13545f415dd672cd8540cd71f735db56",
"removed" : false,
"address" : "0xbb9bc244d798123fde783fcc1c72d3bb8c189413",
"blockHash" : "0x1f716531f40858da4d4b08269f571f9f22c7b8bd921764e8bdf9cb2e0508efa1",
"transactionIndex" : "0x7"
}
],
"gasUsed": 0x33da9,
"cumulativeGasUsed": 0xf98e3
]
*/NOTE: Library is still in development. Domain level objects for all RPC structures are on the roadmap.
After fetching the information you could transparently convert it to suitable objects.
// Get the number of the block in which the transaction occurred
let block = try HexAsDecimalString(
hex: EthNumber(
hex: basicInfo["result"]["blockNumber"].stringValue
)
).value()
print(block)
// 1664614
// Get the recipient of the transaction
let recipient = try EthAddress(
hex: basicInfo["result"]["to"].stringValue
).value().toHexString()
print(recipient)
// bb9bc244d798123fde783fcc1c72d3bb8c189413
// Get the transaction fee in WEI
let gasPrice = EthNumber(
hex: basicInfo["result"]["gasPrice"].stringValue
)
let gasUsed = EthNumber(
hex: advancedInfo["result"]["gasUsed"].stringValue
)
let fee = try HexAsDecimalString(
hex: gasPrice * gasUsed
).value()
print(fee)
// 4247860000000000 WEI = 0,00424786 ETHYou could easily parse any transaction's input by knowing it's ABI or types the data passed into it.
// Parse the transaction input parameters
/*
newProposal(
[0] address _recipient,
[1] uint256 _amount,
[2] string _description,
[3] bytes _transactionData,
[4] uint256 _debatingPeriod,
[5] bool _newCurator
)
*/
// Prepare the transaction's input for parsing - trim the signature of the executed function
let input = ABIMessage(
message: TrimmedPrefixString(
string: SimpleString{
basicInfo["result"]["input"].stringValue
},
prefix: SimpleString{
"0x612e45a3"
}
)
)
// Get the recipient's address
let abiRecipient = try DecodedABIAddress(
abiMessage: input,
index: 0
).value().toHexString()
print(abiRecipient)
// b656b2a9c3b2416437a811e07466ca712f5a5b5a
// Get the description string
let description = try DecodedABIString(
abiMessage: input,
index: 2
).value()
print(description)
// lonely, so lonely
// Get the debating period number
let debatingPeriod = try HexAsDecimalString(
hex: DecodedABINumber(
abiMessage: input,
index: 4
)
).value()
print(debatingPeriod)
// 604800
// Get the boolean flag
let flag = try DecodedABIBoolean(
abiMessage: input,
index: 5
).value()
print(flag)
// true- Timofey Solonin @biboran, abdulowork@gmail.com
- Vadim Koleoshkin @rockfridrich, vadim@zerion.io
Web3Swift is available under the Apache License 2.0. See the LICENSE file for more info.