我正在尝试与我设置的智能合约进行交互。
基本上目标是从 iOS App 5 参数中设置
projectTitle
projectLocation
projectStart
projectEnd
teamType
我希望用户设置这些参数并将其写入 ropsten 测试网络。
我也想在以后用户有需要的时候获取合同信息。
我的 Solidity 代码在 remix 中工作正常，并且合约已经部署：
pragma solidity >=0.4.22 <0.7.0;
contract ProjectContent {
string public projectTitle;
string public projectLocation;
string public projectStart;
string public projectEnd;
string public teamType;
function projectContent(string initialProjectTitle, string initialProjectLocation, string initialProjectStart, string initialProjectEnd, string initialTeamType) public {
projectTitle = initialProjectTitle;
projectLocation = initialProjectLocation;
projectStart = initialProjectStart;
projectEnd = initialProjectEnd;
teamType = initialTeamType;
}
function setContract(string newProjectTitle, string newProjectLocation, string newProjectStart, string newProjectEnd, string newTeamType) public {
projectTitle = newProjectTitle;
projectLocation = newProjectLocation;
projectStart = newProjectStart;
projectEnd = newProjectEnd;
teamType = newTeamType;
}
function getProjectTitle() public view returns (string) {
return projectTitle;
}
function getProjectLocation() public view returns (string) {
return projectLocation;
}
function getProjectStart() public view returns (string) {
return projectStart;
}
function getProjectEnd() public view returns (string) {
return projectEnd;
}
function getTeamType() public view returns (string) {
return teamType;
}
}
我现在的问题是我无法弄清楚如何使用 web3swift 库从区块链中检索数据。我现在就是这样做的：
class ProjectContractViewController: UIViewController, HalfModalPresentable {
@IBOutlet weak var contractABIView: UITextView!
var halfModalTransitioningDelegate: HalfModalTransitioningDelegate?
var contractABI = "[{\"constant\":false,\"inputs\":[{\"name\":\"initialProjectTitle\",\"type\":\"string\"},{\"name\":\"initialProjectLocation\",\"type\":\"string\"},{\"name\":\"initialProjectStart\",\"type\":\"string\"},{\"name\":\"initialProjectEnd\",\"type\":\"string\"},{\"name\":\"initialTeamType\",\"type\":\"string\"}],\"name\":\"projectContent\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":false,\"inputs\":[{\"name\":\"newProjectTitle\",\"type\":\"string\"},{\"name\":\"newProjectLocation\",\"type\":\"string\"},{\"name\":\"newProjectStart\",\"type\":\"string\"},{\"name\":\"newProjectEnd\",\"type\":\"string\"},{\"name\":\"newTeamType\",\"type\":\"string\"}],\"name\":\"setContract\",\"outputs\":[],\"payable\":false,\"stateMutability\":\"nonpayable\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectEnd\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectLocation\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectStart\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getProjectTitle\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"getTeamType\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectEnd\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectLocation\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectStart\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"projectTitle\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"},{\"constant\":true,\"inputs\":[],\"name\":\"teamType\",\"outputs\":[{\"name\":\"\",\"type\":\"string\"}],\"payable\":false,\"stateMutability\":\"view\",\"type\":\"function\"}]"
let str = "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var contractAddress = EthereumAddress("0x11A0c067d7481240dCA57457eff77fc98dEAdE0F")
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
func callContract(Password: String) {
// Get from address from private key
let formattedKey = Password.trimmingCharacters(in: .whitespacesAndNewlines)
let dataKey = Data.fromHex(formattedKey )!
// @@@ use [passKey]
let keystore = try! EthereumKeystoreV3(privateKey: dataKey, password: "")!
let keyData = try! JSONEncoder().encode(keystore.keystoreParams)
// let address = keystore.addresses!.first!.address
let address = keystore.addresses!.first!.address
let ethAddress = EthereumAddress(address)
let infura = Web3.InfuraMainnetWeb3()
// 1
let contract = infura.contract(contractABI, at: contractAddress, abiVersion: 2)
// 2
var options = TransactionOptions.defaultOptions
options.from = keystore.addresses!.first!
// 3
let data = Data.init(hex: str)
let transactionIntermediate = contract?.method("getProjectTitle", parameters: [address] as [AnyObject], extraData: data, transactionOptions: options)
// 4
let result = transactionIntermediate!.call(transactionOptions: options)
switch result {
// 5
case .success(let res):
let ans = res["0"] as! Bool
DispatchQueue.main.async {
completion(Result.Success(ans))
}
case .failure(let error):
DispatchQueue.main.async {
completion(Result.Error(error))
}
}
}
}
我收到了一个错误，因为 result 说：
"调用可以抛出，但是没有标记'try'，错误没有处理"
总的来说，我发现很难建立与智能合约 abi 的交互。
我已经在使用 web3swift 功能发送交易了，它的功能非常棒。
也许有人知道我如何在区块链上记录信息并使用 web3swift 获取它。
可悲的是，互联网上的内容在这方面确实没有帮助。
感谢您的帮助:)
答案 0 :(得分：1)
你很近。从错误 "Call can throw, but it is not marked with 'try' and the error is not handled" 开始，这是由于在不使用 Try Catch 模式的情况下尝试 call 合同函数引起的。按照 web3 库的设计方式，这个模式对于所有的 write 和 call 方法都是必要的。
// Incorrect
let result = transactionIntermediate!.call(transactionOptions: options)
// Correct
do {
let result = try transactionIntermediate!.call(transactionOptions: options)
}catch{
print("Error trying to call method \(error)")
}
此外，我建议您在进行合同调用时将 DispatchQueue.main.async 与 Promise Kit library 一起使用。
ABI 难以阅读且混乱，不建议使用它来帮助查找合同中的可调用方法和参数。相反，我会将合约与 Xcode 一起打开，并通过使用包含将要使用的所有合约方法的枚举或结构。
// Methods available within the contract
enum ContractMethods:String {
case projectContract = "projectContent"
case setContract = "setContract"
case getProjectTitle = "getProjectTitle"
case getProjectLocation = "getProjectLocation"
case getProjectStart = "getProjectStart"
case getProjectEnd = "getProjectEnd"
case getTeamType = "getTeamType"
}
// Usage
ContractMethods.setContract.rawValue
我将 ABI 移动到 xcode 中的一个单独文件中以保持其干净。这是文件的 link。
这是一个很好的例子，可以帮助您入门。查看我的 Github repo 以获得改进版本。希望这会有所帮助，如果您有更多问题，请告诉我。 :)
import UIKit
import web3swift
import PromiseKit
struct Wallet {
let address: String
let data: Data
let name:String
let isHD:Bool
}
struct HDKey {
let name:String?
let address:String
}
var password = "" // leave empty for ganache or use your wallet password
let privateKey = "<PrivateKey>" // Private key of wallet
let walletName = "MyWallet"
let contractAddress = "<ContractAddress>" // 0x11A0c067d7481240dCA57457eff77fc98dEAdE0F
let endpoint = URL(string:"http://127.0.0.1:7545")! // Im using Ganache but it might look like endpoint = URL(string:"https://rinkeby.infura.io/v3/<APIKEY>")!
let abiVersion = 2
class ViewController: UIViewController {
// Mock data used within contract
let projectTitle = "HouseSiding"
let projectLocation = "299 Race Ave. Dacula, GA 30019"
let projectStart = "May 14, 2021"
let projectEnd = "June 15, 2021"
let teamType = "Collaboration"
var web3:web3?
var contract:web3.web3contract?
override func viewDidLoad() {
super.viewDidLoad()
// 1. Create wallet using a private key
let formattedKey = privateKey.trimmingCharacters(in: .whitespacesAndNewlines)
let dataKey = Data.fromHex(formattedKey)!
let keyStore = try! EthereumKeystoreV3(privateKey:dataKey, password: password)!
let keyData = try! JSONEncoder().encode(keyStore.keystoreParams)
let address = keyStore.addresses!.first!.address
let wallet = Wallet(address: address, data: keyData, name: walletName, isHD: false)
// 2. Construct web3 and keystoreManager
do {
web3 = try Web3.new(endpoint)
let data = wallet.data
var keystoreManager: KeystoreManager
if wallet.isHD {
let keystore = BIP32Keystore(data)!
keystoreManager = KeystoreManager([keystore])
}else{
let keystore = EthereumKeystoreV3(data)!
keystoreManager = KeystoreManager([keystore])
}
print(keystoreManager.addresses)
web3!.addKeystoreManager(keystoreManager)
let ethContractAddress = EthereumAddress(contractAddress, ignoreChecksum: true)!
contract = web3!.contract(contractABI, at: ethContractAddress, abiVersion: abiVersion)!
}catch{
print ("Failed to construct contract and/or keystoreManager \(error)")
}
// 3. Create and callout a contract method
//let parameters = [projectTitle,projectLocation,projectStart,projectEnd,teamType] as [AnyObject] // parameters used to created a new project
let parameters = [] as [AnyObject] // no parameters
let response = Promise<Any> { seal in
DispatchQueue.global().async {
// Catch errors within async call
do {
// No extra data for method call
let extraData: Data = Data()
// Options for method call
var options = TransactionOptions.defaultOptions
options.from = EthereumAddress(wallet.address)! // current wallet address
// Leave automatic for gas
options.gasPrice = .automatic
options.gasLimit = .automatic
// Calling get Project title from contract
// NOTE: First call setContract with parameters
let tx = self.contract!.method("getProjectTitle",
parameters: parameters,
extraData: extraData,
transactionOptions: options)
// Depending on the type of call a password might be needed
//if password != nil {
//let result = try tx!.send(password: password)
// seal.resolve(.fulfilled(true))
//}else{
let result = try tx!.call()
// fulfill are result from contract
let anyResult = result["0"] as Any
seal.resolve(.fulfilled(anyResult))
//}
}catch {
// error
seal.reject(error)
}
}
}
response.done({result in
print(result) // Optional(HouseSiding)
})
}
}