Resolution is a library for interacting with blockchain domain names. It can be used to retrieve payment addresses and IPFS hashes for decentralized websites.
Resolution is primarily built and maintained by Unstoppable Domains.
pod 'UnstoppableDomainsResolution', '~> 6.1.0'package.dependencies.append(
.package(url: "https://github.com/unstoppabledomains/resolution-swift", from: "6.1.0")
)pod update UnstoppableDomainsResolutionpackage.dependencies.append(
.package(url: "https://github.com/unstoppabledomains/resolution-swift", from: "<latest version number>")
)- Create an instance of the Resolution class
- Call any method of the Resolution class asyncronously
NOTE: make sure an instance of the Resolution class is not deallocated until the asyncronous call brings in the result. Your code is the only owner of the instance so keep it as long as you need it.
import UnstoppableDomainsResolution
// obtain a key by following this document https://docs.unstoppabledomains.com/domain-distribution-and-management/quickstart/retrieve-an-api-key/#api-key
guard let resolution = try? Resolution(apiKey: "<api_key>") else {
print ("Init of Resolution instance failed...")
return
}NOTE: The
apiKeyis only used resolve domains from UNS. Behind the scene, it still uses the default ZNS (Zilliqa) RPC url. For additional control, please specify your ZNS configuration.
import UnstoppableDomainsResolution
// obtain a key by following this document https://docs.unstoppabledomains.com/domain-distribution-and-management/quickstart/retrieve-an-api-key/#api-key
guard let resolution = try? Resolution(
apiKey: "<api_key>",
znsLayer: NamingServiceConfig(
providerUrl: "https://api.zilliqa.com",
network: "mainnet")
) else {
print ("Init of Resolution instance with default parameters failed...")
return
}The Configurations struct that is used for configuring each connected naming service.
Library supports three networks at the moment Ethereum, Polygon and Zilliqa. You can update each network separately.
import UnstoppableDomainsResolution
// obtain a key from https://www.infura.io
let resolution = try Resolution(configs: Configurations(
uns: UnsLocations = UnsLocations(
layer1: NamingServiceConfig(
providerUrl: "https://mainnet.infura.io/v3/<infura_api_key>",
network: "mainnet"),
layer2: NamingServiceConfig(
providerUrl: "https://polygon-mainnet.infura.io/v3/<infura_api_key>",
network: "polygon-mainnet"),
znsLayer: NamingServiceConfig(
providerUrl: "https://api.zilliqa.com",
network: "mainnet")
)
);addr(domain: String, ticker: String)
This API is used to retrieve wallet address for single address record. (See Cryptocurrency payment section for the record format)
With brad.crypto has crypto.ETH.address on-chain:
resolution.addr(domain: "brad.crypto", ticker: "eth") { (result) in
switch result {
case .success(let returnValue):
ethAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected Eth Address, but got \(error)")
}
}multiChainAddress(domain: String, ticker: String, chain: String)
This API is used to retrieve wallet address for multi-chain address records. (See multi-chain currency)
With brad.crypto has crypto.USDT.version.ERC20.address and crypto.USDT.version.OMNI.address on-chain:
resolution.multiChainAddress(domain: "brad.crypto", ticker: "USDT", chain: "ERC20") { (result) in
switch result {
case .success(let returnValue):
ethAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected Eth Address, but got \(error)")
}
}addr(domain: String, network: String, token: String)
This (Beta) API can be used to retrieve wallet address for single chain and multi-chain address records.
With brad.crypto has crypto.ETH.address and crypto.USDT.version.ERC20.address on-chain:
// single chain address
resolution.addr(domain: "brad.crypto", network: "eth", token: "eth") { (result) in
switch result {
case .success(let returnValue):
ethAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected Eth Address, but got \(error)")
}
}
// multi-chain address
resolution.multiChainAddress(domain: "brad.crypto", ticker: "ETH", chain: "USDT") { (result) in
switch result {
case .success(let returnValue):
usdtAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected USDT Address, but got \(error)")
}
}Note that the API will infer
ERC20standard asETHnetwork.
The API can also be used by crypto exchanges to infer wallet addresses. In centralized exchanges, users have same wallet addresses on different networks with same wallet family. (See Blockchain Family, Network, Token Level Addresses section for the record format)
With brad.crypto only has token.EVM.address record on-chain.
The API resolves to same wallet address for tokens live on EVM compatible networks.
// infer USDT on ETH network
resolution.multiChainAddress(domain: "brad.crypto", network: "ETH", token: "USDT") { (result) in
switch result {
case .success(let returnValue):
usdtOnEthAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected USDT Address, but got \(error)")
}
}
// infer ETH token on ETH network
resolution.multiChainAddress(domain: "brad.crypto", network: "ETH", token: "ETH") { (result) in
switch result {
case .success(let returnValue):
ethTokenOnEthAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected Eth Address, but got \(error)")
}
}
// infer USDT token on ETH network
resolution.multiChainAddress(domain: "brad.crypto", network: "AVAX", token: "USDT") { (result) in
switch result {
case .success(let returnValue):
usdtOnAvaxAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected USDT Address, but got \(error)")
}
}With brad.crypto only has token.EVM.ETH.address
record on chain. The API resolves to the same wallet address for tokens
specifically on Ethereum network.
// infer USDT on ETH network
resolution.multiChainAddress(domain: "brad.crypto", network: "ETH", token: "USDT") { (result) in
switch result {
case .success(let returnValue):
usdtOnEthAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected USDT Address, but got \(error)")
}
}
// infer ETH token on ETH network
resolution.multiChainAddress(domain: "brad.crypto", network: "ETH", token: "ETH") { (result) in
switch result {
case .success(let returnValue):
ethTokenOnEthAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected Eth Address, but got \(error)")
}
}
// the API try to derive address for Avalanche network
resolution.multiChainAddress(domain: "brad.crypto", network: "AVAX", token: "USDT") { (result) in
switch result {
case .success(let returnValue):
usdtOnAvaxAddress = returnValue
domainReceived.fulfill()
case .failure(let error):
XCTFail("Expected USDT Address, but got \(error)")
}
}The API is compatible with other address formats. If a domain has multiple address formats set, it will follow the algorithm described as follow:
if a domain has following records set:
token.EVM.address
crypto.USDC.version.ERC20.address
token.EVM.ETH.USDC.address
crypto.USDC.address
token.EVM.ETH.address
getAddress(domain, 'ETH', 'USDC') will lookup records in the following order:
1. token.EVM.ETH.USDC.address
2. crypto.USDC.address
3. crypto.USDC.version.ERC20.address
4. token.EVM.ETH.address
5. token.EVM.address
the batchOwners(domains: _, completion: _ ) method adds additional convenience when making multiple domain owner queries.
This method is only compatible with uns-based domains. Using this method with any other domain type will throw the error:
ResolutionError.methodNotSupported.
As opposed to the single owner(domain: _, completion: _) method, this batch request will return an array of owners [String?]. If the the domain is not registered or its value is null, the corresponding array element of the response will be nil without throwing an error.
resolution.batchOwners(domains: ["brad.crypto", "homecakes.crypto"]) { result in
switch result {
case .success(let returnValue):
// returnValue: [String: String?] = <map of domains to owner address>
let domainOwner = returnValue
case .failure(let error):
XCTFail("Expected owner, but got \(error)")
}
}
resolution.locations(domains: ["brad.crypto", "homecakes.crypto"]) { result in
switch result {
case .success(let returnValue):
// returnValue: [String: String?] = <map of domains to domain locations>
let locations = returnValue
case .failure(let error):
XCTFail("Expected owner, but got \(error)")
}
}Make sure your app has AppTransportSecurity settings to allow HTTP access to the
https://main-rpc.linkpool.iodomain.
By default, this library uses the native iOS networking API to connect to the internet. If you want the library to use your own networking layer instead, you must conform your networking layer to the NetworkingLayer protocol. This protocol requires three methods to be implemented:
func makeHttpPostRequest(url:, httpMethod:, httpHeaderContentType:, httpBody:, completion:)func makeHttpGetRequest(url: URL, completion:)mutating func addHeader(header: String, value: String)
Using these methods will bypass the default behavior and delegate the request to your own networking code.
For example, construct the Resolution instance like so:
let customNetworking = MyNetworkingApi()
let resolution = try Resolution(configs: Configurations(
uns: UnsLocations = UnsLocations(
layer1: NamingServiceConfig(
providerUrl: "https://mainnet.infura.io/v3/<infura_api_key>",
network: "mainnet",
networking: customNetworking),
layer2: NamingServiceConfig(
providerUrl: "https://polygon-mainnet.infura.io/v3/<infura_api_key>",
network: "polygon-mainnet",
networking: customNetworking),
znsLayer: NamingServiceConfig(
providerUrl: "https://api.zilliqa.com",
network: "mainnet")
)
);If the domain you are attempting to resolve is not registered or doesn't contain the information you are requesting, this framework will return a ResolutionError with the possible causes below. We advise creating customized errors in your app based on the return value of the error.
enum ResolutionError: Error {
case unregisteredDomain
case unsupportedDomain
case recordNotFound
case recordNotSupported
case unsupportedNetwork
case unspecifiedResolver
case unknownError
case proxyReaderNonInitialized
case registryAddressIsNotProvided
case inconsistentDomainArray
case methodNotSupported
case tooManyResponses
case executionReverted
case badRequestOrResponse
case unsupportedServiceName
case invalidDomainName
case contractNotInitialized
case reverseResolutionNotSpecified
case unauthenticatedRequest
case requestBeingRateLimited
}Please see the Resolution-Swift Error Codes page for details of the specific error codes.
Contributions to this library are more than welcome. The easiest way to contribute is through GitHub issues and pull requests.
Resolution library relies on environment variables to load TestNet RPC Urls. This way, our keys don't expose directly to the code. These environment variables are:
- L1_TEST_NET_RPC_URL
- L2_TEST_NET_RPC_URL
Use swift build to build, and swift test -v to run the tests
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