SwiftBSV

A library to help you create Bitcoin transactions in Swift.

The goal is to mimic the https://github.com/moneybutton/bsv/ lib as close as possible. I've used multiple existing open source Bitcoin Swift libraries as a starting point. This project is in active development and will continue to change significantly.

Todo:

• BInt (Big Number)
• Base58Check
• Point (Elliptic Curve Points)
• PublicKeys
• PrivateKeys
• Bip39 (Mnemonic)
• Bip32 (HD Wallets)
• TxBuilder
• more...

Installation

Add this to your project using Swift Package Manager. In Xcode that is simply: File > Swift Packages > Add Package Dependency... and you're done. Alternative installations options are shown below for legacy projects.

CocoaPods

If you are already using CocoaPods, just add 'SwiftBSV' to your Podfile then run pod install.

Carthage

If you are already using Carthage, just add to your Cartfile:

github "wtsnz/SwiftBSV" ~> 0.1

Then run carthage update to build the framework and drag the built SwiftBSV.framework into your Xcode project.

Usage Examples

BIP-39: Mnemonic Seeds

let mnemonic = Bip39.create()
let seed = Bip39.createSeed(mnemonic: mnemonic)
let rootKey = Bip32(seed: seed, network: .mainnet)

print(rootKey.address)

// 1C8eycEadLHZZfRkchqTC3e72fRNNfbXs3

Bitcoin Signed Messages

Sign a message

let message = "hello!"
let privateKey = PrivateKey()
let address = privateKey.address
let sigString = BitcoinSignedMessage.sign(message: message, privateKey: privateKey)
print(sigString)

// H5wZz9N2+O8oHCMfZBE5nbeM6dr2ZwpD6cKhC0q1lPi/A1t9KV5VO0vTL2kRg8Hg7XSmZl1cviZFj4TkfLAGT9E=

Verify a message

let message = "hello!"
let address = Address(fromString: "1D7ZaBLeT3FFr1mcKAWorZHdE18kEVvuaY")!

let sigString = "IOsRLk8/CBpLvOecpV0kh4ajjgpUH04T3kkJRPJng5kMOe3Az0gwGx2n8dHyooGykrqB6SuMCPtahZ5EN/TcZzg="

let valid = BitcoinSignedMessage.verify(message: message, signature: sigString, address: address)
print(valid)

// true

Create a Transaction

let privateKey = PrivateKey(data: wallet.privateKey)
let publicKey = privateKey.publicKey
let address = publicKey.address

let txb = TxBuilder()
    .setFeePerKb(500)
    .setChangeAddress(address)

// Add inputs to the transaction
var numberOfInputs = 0
for utxo in utxos {
    let txHashBuf = Data(Data(hex: utxo.txId).reversed())
    let txOut = TransactionOutput(
        value: utxo.satoshis,
        lockingScript: Data(hex: utxo.script)
    )

    txb.inputFromPubKeyHash(
        txHashBuffer: txHashBuf,
        txOutNum: utxo.outputIndex,
        txOut: txOut,
        pubKey: publicKey
    )

    numberOfInputs = numberOfInputs + 1
}

// Add a data output

var script = try! Script().append(.OP_FALSE).append(.OP_RETURN).appendData("hello, world!".data(using: .utf8)!)

txb.outputToScript(
    value: 0,
    script: script
)

// Add an output to another Address (pay-to-pubkey-hash)
let value = UInt64(payee.amount * 100_000_000)
txb.outputToAddress(value: value, address: Address(fromString: payee.to)!)

// Build, using all the inputs

try! txb.build(useAllInputs: true)

// Finally sign the built transaction
for input in 0..<numberOfInputs {
    txb.signInTx(nIn: input, privateKey: privateKey)
}


// Do something with the signed transaction!
txb.transaction

Author

Will Townsend

License

SwiftBSV is available under the MIT license. See the LICENSE file for more information.

Thanks to

This project is a mashup of a bunch of open source projects, and many original contributions and wouldn't have been possible without the following projects:

• https://github.com/KevinVitale/WalletKit
• https://github.com/yuzushioh/HDWalletKit
• https://github.com/yenom/BitcoinKit
• https://github.com/moneybutton/bsv