BitcoinKit.Swift

Bitcoin wallet toolkit for Swift. This is a full implementation of SPV node including wallet creation/restore, synchronization with network, send/receive transactions, and more.

Features

• Full SPV implementation for fast mobile performance
• Send/Receive Legacy transactions (P2PKH, P2PK, P2SH)
• BIP32 hierarchical deterministic wallets implementation.
• BIP39 mnemonic code for generating deterministic keys.
• BIP44 multi-account hierarchy for deterministic wallets.
• BIP21 URI schemes, which include payment address, amount, label and other params

BitcoinKit.swift

• Send/Receive Segwit transactions (P2WPKH)
• Send/Receive Segwit transactions compatible with legacy wallets (P2WPKH-SH)
• base58, bech32

Usage

Initialization

Kit requires you to provide mnemonic phrase when it is initialized:

let words = ["word1", ... , "word12"]

Bitcoin

let bitcoinKit = BitcoinKit(withWords: words, walletId: "bitcoin-wallet-id", syncMode: .api, networkType: .mainNet)

Kit can be configured to work in .mainNet or .testNet.

syncMode parameter

Kit can restore existing wallet or create a new one. When restoring, it generates addresses for given wallet according to bip44 protocol, then it pulls all historical transactions for each of those addresses. This is done only once on initial sync. syncMode parameter defines where it pulls historical transactions from. When they are pulled, it continues to sync according to SPV protocol no matter which syncMode was used for initial sync. There are 3 modes available:

• .full: Fully synchronizes from peer-to-peer network starting from the block when bip44 was introduced. This mode is the most private (since it fully complies with SPV protocol), but it takes approximately 2 hours to sync up to now (June 10, 2019).
• .api: Transactions before checkpoint are pulled from API(currently Insight API or BcoinAPI). Then the rest is synchronized from peer-to-peer network. This is the fastest one, but it's possible for an attacker to learn which addresses you own. Checkpoints are updated with each new release and hardcoded so the blocks validation is not broken.
• .newWallet: No need to pull transactions.

Additional parameters:

• confirmationsThreshold: Minimum number of confirmations required for an unspent output in incoming transaction to be spent (default: 6)
• minLogLevel: Can be configured for debug purposes if required.

Starting and Stopping

Kit require to be started with start command. It will be in synced state as long as it is possible. You can call stop to stop it

bitcoinKit.start()
bitcoinKit.stop()

Getting wallet data

Kit hold all kinds of data obtained from and needed for working with blockchain network

Current Balance

Balance is provided in Satoshi:

bitcoinKit.balance

// 2937096768

Last Block Info

Last block info contains headerHash, height and timestamp that can be used for displaying sync info to user:

bitcoinKit.lastBlockInfo 

// ▿ Optional<BlockInfo>
//  ▿ some : BlockInfo
//    - headerHash : //"00000000000041ae2164b486398415cca902a41214cad72291ee04b212bed4c4"
//    - height : 1446751
//    ▿ timestamp : Optional<Int>
//      - some : 1544097931

Receive Address

Get an address which you can receive coins to. Receive address is changed each time after you actually get a transaction in which you receive coins to that address

bitcoinKit.receiveAddress

// "mgv1KTzGZby57K5EngZVaPdPtphPmEWjiS"

Transactions

Kit have transactions(fromHash: nil, limit: nil) methods which return Single<TransactionInfo>(for BitcoinKit and BitcoinCashKit) RX Single Observers.

TransactionInfo:

//   ▿ TransactionInfo
//     - transactionHash : "0f83c9b330f936dc4a2458b7d3bb06dce6647a521bf6d98f9c9d3cdd5f6d2a73"
//     - transactionIndex : 500000
//     ▿ from : 2 elements
//       ▿ 0 : TransactionAddressInfo
//         - address : "mft8jpnf3XwwqhaYSYMSXePFN85mGU4oBd"
//         - mine : true
//       ▿ 1 : TransactionAddressInfo
//         - address : "mnNS5LEQDnYC2xqT12MnQmcuSvhfpem8gt"
//         - mine : true
//     ▿ to : 2 elements
//       ▿ 0 : TransactionAddressInfo
//         - address : "n43efNftHQ1cXYMZK4Dc53wgR6XgzZHGjs"
//         - mine : false
//       ▿ 1 : TransactionAddressInfo
//         - address : "mrjQyzbX9SiJxRC2mQhT4LvxFEmt9KEeRY"
//         - mine : true
//     - amount : -800378
//     ▿ blockHeight : Optional<Int>
//       - some : 1446602
//    ▿ timestamp : Optional<Int>
//       - some : 1543995972

Creating new transaction

In order to create new transaction, call send(to: String, value: Int, feeRate: Int) method on Kits

try bitcoinKit.send(to: "mrjQyzbX9SiJxRC2mQhT4LvxFEmt9KEeRY", value: 1000000, feeRate: 10000)

This first validates a given address and amount, creates new transaction, then sends it over the peers network. If there's any error with given address/amount or network, it raises an exception.

Validating transaction before send

One can validate address and fee by using following methods:

try bitcoinKit.validate(address: "mrjQyzbX9SiJxRC2mQhT4LvxFEmt9KEeRY")
try bitcoinKit.fee(for: 1000000, toAddress: "mrjQyzbX9SiJxRC2mQhT4LvxFEmt9KEeRY", senderPay: true, feeRate: 10000)

senderPay parameter defines who pays the fee

Parsing BIP21 URI

You can use parse method to parse a BIP21 URI:

bitcoinKit.parse(paymentAddress: "bitcoin:175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W?amount=50&label=Luke-Jr&message=Donation%20for%20project%20xyz")

// ▿ BitcoinPaymentData
//   - address : "175tWpb8K1S7NmH4Zx6rewF9WQrcZv245W"
//   - version : nil
//   ▿ amount : Optional<Double>
//     - some : 50.0
//   ▿ label : Optional<String>
//     - some : "Luke-Jr"
//   ▿ message : Optional<String>
//     - some : "Donation for project xyz"
//   - parameters : nil

Subscribing to BitcoinKit data

Kits provide with data like transactions, blocks, balance, kits state in real-time. BitcoinCoreDelegate protocol must be implemented and set to Kits instance to receive that data.

class Manager {

	init(words: [String]) {
		bitcoinKit = BitcoinKit(withWords: words, walletId: "bitcoin-wallet-id")
        bitcoinKit.delegate = self
    }

}

extension Manager: BitcoinCoreDelegate {

    func transactionsUpdated(inserted: [TransactionInfo], updated: [TransactionInfo]) {
    }

    func transactionsDeleted(hashes: [String]) {
    }

    func balanceUpdated(balance: Int) {
    }

    func lastBlockInfoUpdated(lastBlockInfo: BlockInfo) {
    }

    public func kitStateUpdated(state: BitcoinCore.KitState) {
		// BitcoinCore.KitState can be one of 3 following states:
		// .synced
		// .syncing(progress: Double)
		// .notSynced
		// 
		// These states can be used to implement progress bar, etc
    }
    
}

Listener events are run in a dedicated background thread. It can be switched to main thread by setting the delegateQueue property to DispatchQueue.main

bitcoinKit.delegateQueue = DispatchQueue.main

Prerequisites

• Xcode 10.0+
• Swift 5+
• iOS 11+

Installation

Swift Package Manager

The Swift Package Manager is a tool for automating the distribution of Swift code and is integrated into the swift compiler. It is in early development, but DashCryptoKit does support its use on supported platforms.

Once you have your Swift package set up, adding DashCryptoKit as a dependency is as easy as adding it to the dependencies value of your Package.swift.

dependencies: [
    .package(url: "https://github.com/horizontalsystems/BitcoinKit.Swift.git", .upToNextMajor(from: "1.0.0"))
]

Example Project

All features of the library are used in example project. It can be referred as a starting point for usage of the library.

License

The BitcoinKit toolkit is open source and available under the terms of the MIT License.