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EOSIO SDK for Swift

Swift 5.2

EOSIO SDK for Swift is a set of components for integrating with EOSIO-based blockchains. It contains:

  • EosioSwift, the core component for communicating and transacting with EOSIO-based blockchains using the EOS RPC API.
  • ABIEOS Serialization Provider, a pluggable serialization provider for EosioSwift. Serialization providers are responsible for ABI-driven transaction and action serialization and deserialization between JSON and binary data representations. This particular serialization provider wraps ABIEOS, a C/C++ library that facilitates this conversion.
  • ECC, a component for working with public and private keys, cryptographic signatures, encryption/decryption, etc.
  • Softkey Signature Provider, an example pluggable signature provider for EosioSwift. It allows for signing transactions using in-memory K1 keys.

To date, EOSIO SDK for Swift has only been tested on iOS. The goal, however, is for the core library to run anywhere Swift runs, adding other targets (macOS, watchOS, tvOS) as the library matures.

All product and company names are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.

Contents​

Prerequisites​

  • Xcode 11 or higher
  • CocoaPods 1.9.3 or higher OR
  • Swift Package Manager (SPM) 5.2 or higher
  • For iOS, iOS 12+

Installation​

Swift Package Manager​

Depending on the component(s) you wish to use, the appropriate dependencies will also be installed for you. For example, if you wished to use EosioSwiftAbieosSerializationProvider, then the main EosioSwift component would also be installed.

If you wish to use all of the components, add the EosioSwift, EosioSwiftAbieosSerializationProvider, EosioSwiftEcc and EosioSwiftSoftkeySignatureProvider products from https://github.com/eosnetworkfoundation/mandel-swift to your application dependencies.

Or to include it into a library, add the following to your Package.swift definition:

// swift-tools-version:5.2
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "MyName",
    platforms: [
        .iOS(.v12)
    ],
    products: [
        // Products define the executables and libraries produced by a package, and make them visible to other packages.
        .library(
            name: "MyLibrary",
            targets: ["MyLibrary"]),
    ],
    dependencies: [
        // Dependencies declare other packages that this package depends on.
        // .package(url: /* package url */, from: "1.0.0"),
        .package(name: "EosioSwift", url: "https://github.com/eosnetworks/mandel-swift", from: "1.0.0"))
    ],
    targets: [
        // Targets are the basic building blocks of a package. A target can define a module or a test suite.
        // Targets can depend on other targets in this package, and on products in packages which this package depends on.
        .target(
            name: "MyLibrary",
            dependencies: [
                .product(name: "EosioSwift", package: "EosioSwift"),
                .product(name: "EosioSwiftAbieosSerializationProvider", package: "EosioSwift"),
                .product(name: "EosioSwiftEcc", package: "EosioSwift"),
                .product(name: "EosioSwiftSoftkeySignatureProvider", package: "EosioSwift"),
        ]),
        .testTarget(
            name: "MyLibraryTests",
            dependencies: ["MyLibrary"]),
    ]
)

Technically, in the full definition, not all of the components would have to be specified as dependencies since EosioSwiftSoftkeySignatureProvider depends on EosioSwiftEcc and EosioSwift and would include them automatically, but all products are listed here for illustration purposes.

If you only want some of the components, you can remove the unwanted dependencies in the product name definition for your target.

CocoaPods​

All of the EOSIO SDK for Swift components are separated as subspecs in Cocoapods. If you install the entire pod from EOSIO SDK for Swift, you will get the main EosioSwift API, ABIEOS Serialization Provider, ECC and Softkey Signature Provider. To do this, add the following to your Podfile:

use_frameworks!

target "Your Target" do
  pod "EosioSwift", "~> 1.0.0"
end

Then run pod install. And you're all set for the Basic Usage example!

If you wish to use only some of the components, add the subspecs you want out of the list below to your Podfile:

use_frameworks!

target "Your Target" do
  pod "EosioSwift/Core", "~> 1.0.0" # The main Eosio Swift API
  pod "EosioSwift/AbieosSerializationProvider", "~> 1.0.0" # serialization provider
  pod "EosioSwift/Ecc", "~> 1.0.0" # ECC, mostly a dependency, normally do not need to specify
  pod "EosioSwift/SoftkeySignatureProvider", "~> 1.0.0" # experimental signature provider for development only

end

Then run pod install. And you're all set for the Basic Usage example!

Basic Usage​

Working With Transactions​

Transactions are instantiated as an EosioTransaction and must then be configured with a number of providers prior to use. (See Provider Protocol Architecture below for more information about providers.)

import EosioSwift
import EosioSwiftAbieosSerializationProvider
import EosioSwiftSoftkeySignatureProvider

Then, inside a do...catch or throwing function, do the following:

let transaction = EosioTransaction()
transaction.rpcProvider = EosioRpcProvider(endpoint: URL(string: "http://localhost:8888")!)
transaction.serializationProvider = EosioAbieosSerializationProvider()
transaction.signatureProvider = try EosioSoftkeySignatureProvider(privateKeys: ["yourPrivateKey"])

/// Actions can now be added to the transaction, which can, in turn, be signed and broadcast:

let action = try EosioTransaction.Action(
    account: EosioName("eosio.token"),
    name: EosioName("transfer"),
    authorization: [EosioTransaction.Action.Authorization(
        actor: EosioName("useraaaaaaaa"),
        permission: EosioName("active"))
    ],
    data: Transfer(
        from: EosioName("useraaaaaaaa"),
        to: EosioName("useraaaaaaab"),
        quantity: "42.0000 SYS",
        memo: "")
)

transaction.add(action: action)

transaction.signAndBroadcast { (result) in
    switch result {
    case .failure (let error):
        // Handle error.
    case .success:
        // Handle success.
    }
}

Starting with version 1.0, it is possible to configure transactions to use the last irreversible block rather than a block blocksBehind the current head block of the chain. The number of blocksBehind or the expireSeconds can also be adjusted. This is done by modifying the Transaction.Config before calling prepare, sign or signAndBroadcast. When useLastIrreversible is true, then blocksBehind is ignored. Transaction.Config defaults useLastIrreversible to true to help minimize micro-forking of transactions under certain conditions.

let transaction = EosioTransaction()
transaction.rpcProvider = EosioRpcProvider(endpoint: URL(string: "http://localhost:8888")!)
transaction.serializationProvider = EosioAbieosSerializationProvider()
transaction.signatureProvider = try EosioSoftkeySignatureProvider(privateKeys: ["yourPrivateKey"])

// Modify the transaction configuration.
transaction.config.useLastIrreversible = false

// Modify expireSeconds if desired.
transaction.config.expireSeconds = 60 * 8

// Add actions, sign, broadcast etc. as shown above...

The Transaction Factory​

Alternatively, to avoid having to set the providers on every transaction, you can use the EosioTransactionFactory convenience class, as follows:

let rpcProvider = EosioRpcProvider(endpoint: URL(string: "http://localhost:8888")!)
let signatureProvider = try EosioSoftkeySignatureProvider(privateKeys: ["yourPrivateKey"])
let serializationProvider = EosioAbieosSerializationProvider()

let myTestnet = EosioTransactionFactory(rpcProvider: rpcProvider, signatureProvider: signatureProvider, serializationProvider: serializationProvider)

let transaction = myTestnet.newTransaction()
// add actions, sign and broadcast!

let anotherTransaction = myTestnet.newTransaction()
// add actions, sign and broadcast!
...

Usage With PromiseKit​

Most EosioTransaction and RPC endpoint methods will return Promises if you ask them. Simply call the method with .promise as the first parameter and drop the callback. For example:

firstly {
    transaction.signAndBroadcast(.promise)
}.done { _ in
    // Handle success.
}.catch { error in
    // Handle error.
}

ABIEOS Serialization Provider Usage​

If you wish to use ABIEOS Serialization Provider directly, its public methods can be called like this:

let abieos: EosioAbieosSerializationProvider? = EosioAbieosSerializationProvider()
let hex = "1686755CA99DE8E73E1200" // some binary data
let json = "{"name": "John"}" // some JSON

let jsonToBinaryTransaction = try? abieos?.serializeTransaction(json: json)
let binaryToJsonTransaction = try? abieos?.deserializeTransaction(hex: hex)

ECC Usage​

ECC provides the following methods, among others. This list will expand as more are added.

  • EosioEccSign.signWithK1(...): Sign data with a K1 key for validation on an EOSIO chain.
  • EccRecoverKey.recoverPublicKey(...): Recover a public key from a private key or from a signature and message.
  • EccRecoverKey.recid(...): Get the Recovery ID for a signature, message and target public key.

Softkey Signature Provider Usage​

Important: Softkey Signature Provider stores keys in memory and is therefore not secure. It should only be used for development purposes. In production, we strongly recommend using a signature provider that interfaces with a secure vault, authenticator or wallet.

Generally, signature providers are called by EosioTransaction during signing. (See an example here.) If you find, however, that you need to get available keys or request signing directly, this library can be invoked as follows:

let signProvider = try? EosioSoftkeySignatureProvider(privateKeys: privateKeysArray)
let publicKeysArray = signProvider?.getAvailableKeys() // Returns the public keys.

To sign an EosioTransaction, create an EosioTransactionSignatureRequest object and call the EosioSoftkeySignatureProvider.signTransaction(request:completion:) method with the request:

var signRequest = EosioTransactionSignatureRequest()
signRequest.serializedTransaction = serializedTransaction
signRequest.publicKeys = publicKeys
signRequest.chainId = chainId

signProvider.signTransaction(request: signRequest) { (response) in
    ...
}

Key Management and Signing Utilities​

Utilities for key generation and management and other signing functionality can be found in the EOS SDK for Swift: Vault library.

Other Code Examples​

More examples can be found in the EXAMPLES.md document.

Code Documentation​

Please refer to the generated code documentation at https://github.com/eosnetworkfoundation/mandel-swift/ or by cloning this repo and opening any of the following files in your browser:

  • docs/EosioSwift/index.html
  • docs/EosioSwiftAbieosSerializationProvider/index.html
  • docs/EosioSwiftEcc/index.html
  • docs/EosioSwiftSoftkeySignatureProvider/index.html

Documentation can be regenerated or updated by running the update_documentation.sh script in the repo.

Provider Protocol Architecture​

The core EOS SDK for Swift library uses a provider-protocol-driven architecture to provide maximum flexibility in a variety of environments and use cases. EosioTransaction leverages those providers to prepare and process transactions. EOS SDK for Swift exposes four protocols. You, the developer, get to choose which conforming implementations to use.

Signature Provider Protocol​

The Signature Provider abstraction is arguably the most useful of all of the EOS SDK for Swift providers. It is responsible for:

  • finding out what keys are available for signing (getAvailableKeys), and
  • requesting and obtaining transaction signatures with a subset of the available keys (signTransaction).

By simply switching out the signature provider on a transaction, signature requests can be routed any number of ways. Need software signing? Configure the EosioTransaction with the Softkey Signature Provider signature provider. Need a signature from keys in the platform's Keychain or Secure Enclave? Take a look at the Vault Signature Provider. Need signatures from a wallet on the user's device? A signature provider can do that too!

All signature providers must conform to the EosioSignatureProviderProtocol Protocol.

EOSIO SDK for Swift does include a signature provider implementation; EosioSoftkeySignatureProvider, an example signature provider for signing transactions using K1 keys in memory. This signature provider stores keys in memory and is therefore not secure. It should only be used for development purposes. In production, we strongly recommend using a signature provider that interfaces with a secure vault, authenticator or wallet.

While it is possible to use EosioSoftkeySignatureProvider, Vault Signature Provider, a signature provider implementation for signing transactions using keys stored in Keychain or the device's Secure Enclave, is strongly recommended.

RPC Provider Protocol​

The RPC Provider is responsible for all RPC calls to nodeos, as well as general network handling (Reachability, retry logic, etc.) While EOSIO SDK for Swift includes an RPC Provider implementation, it must still be set explicitly when creating an EosioTransaction, as it must be instantiated with an endpoint. (The default implementation suffices for most use cases.)

Serialization Provider Protocol​

The Serialization Provider is responsible for ABI-driven transaction and action serialization and deserialization between JSON and binary data representations. These implementations often contain platform-sensitive C++ code and larger dependencies. EOSIO SDK for Swift does include a serialization provider implementation.

ABI Provider Protocol​

The ABI Provider is responsible for fetching and caching ABIs for use during serialization and deserialization. If none is explicitly set on the EosioTransaction, the default EosioAbiProvider will be used. (The default implementation suffices for most use cases.)

RPC: Using the Default RPC Provider​

EOSIO Swift includes a default RPC Provider implementation (EosioRpcProvider) for communicating with EOSIO nodes using the EOSIO RPC API. Alternate RPC providers can be used assuming they conform to the minimal EosioRpcProviderProtocol. The core EOSIO SDK for Swift library depends only on five of the six RPC endpoints set forth in that Protocol. pushTransaction is no longer used by the core library but has been retained for backwards compatibility. Other endpoints, however, are exposed in the default EosioRpcProvider.

Calls can be made to any of the available endpoints as follows:

rpcProvider.getInfo { (infoResponse) in
    switch infoResponse {
    case .failure(let error):
        // handle the error
    }
    case .success(let info) {
        // do stuff with the info!
        print(info.chainId)
    }
}

Attempts are made to marshall the responses into convenient Swift structs. More deeply nested response properties may be presented as a dictionary.

Each response struct will also contain a _rawResponse property. In the event the returned struct is missing a property you were expecting from the response, inspect the _rawResponse. You will likely find it there.

Response structs are currently incomplete. Some responses will only return the _rawResponse. We aim to continue improving response marshalling. And we invite you to help us improve responses too.

Want to help?​

Interested in contributing? That's awesome! Here are some Contribution Guidelines and the Code of Conduct.

We're always looking for ways to improve EOSIO SDK for Swift. Check out our #enhancement Issues for ways you can pitch in.

License​

MIT

Important​

See LICENSE for copyright and license terms. We make our contribution on a voluntary basis as a member of the EOS community and is not responsible for ensuring the overall performance of the software or any related applications. We make no representation, warranty, guarantee or undertaking in respect of the software or any related documentation, whether expressed or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and noninfringement. In no event shall we be liable for any claim, damages or other liability, whether in an action of contract, tort or otherwise, arising from, out of or in connection with the software or documentation or the use or other dealings in the software or documentation. Any test results or performance figures are indicative and will not reflect performance under all conditions. Any reference to any third party or third-party product, service or other resource is not an endorsement or recommendation by Block.one. We are not responsible, and disclaim any and all responsibility and liability, for your use of or reliance on any of these resources. Third-party resources may be updated, changed or terminated at any time, so the information here may be out of date or inaccurate. Any person using or offering this software in connection with providing software, goods or services to third parties shall advise such third parties of these license terms, disclaimers and exclusions of liability. Block.one, EOS, EOSIO Labs, EOS Network Foundation.

Wallets and related components are complex software that require the highest levels of security. If incorrectly built or used, they may compromise users’ private keys and digital assets. Wallet applications and related components should undergo thorough security evaluations before being used. Only experienced developers should work with this software.