App Pic


Swift 5 web3


Native iOS Mobile Reference Application For Celo DAO/ReFi Management projects.


This project is a submission for an Gitcoin bounty by the Celo Network. The goal was to develop a native iOS reference application to inspire web3 projects.


  • Crypta iOS

    • iOS 15.2+
    • Xcode 13.2.1+
    • Swift 5+
    • Cocoapods
  • MetaMask

    • Celo

Quick Start

? Crypta iOS App

  1. Open your terminal and Git clone the repo

    git clone
  2. Install Podfile

    With the same terminal cd into Crypta2.0 and install

    cd Crypta/Crypta2.0
    pod install

    If your running on M1 chip use

    arch -x86_64 pod install

    Wait for the pods to install

  3. Start Xcode and open up the workspace

    Build and launch the app

    Make sure you select a iOS simulator

  4. Send Funds to the app

When launching for the first time login you will be prompted to create a new password for your built wallet. When completed you will be navigated to the GroupsView. You will need your password through the app to sign/send transactions.

Before creating groups and voting you must add some liquidity to the app. This will be used to pay for the gas price associated with writing to the smart contract.

  1. Navigate over the profile view then press the qr code this will copy your address.

  2. Then with google go to Alfajores Testnet Faucet and paste your address then press to send.

  3. Press refresh on the app and watch balance be updated

  4. Using the app

    You can now participate in create groups, proposals and voting.

? Smart Contract

Soon too come.

As of now the contract is deployed on Alfajores Testnet and the ABI is still the same.

  Address: 0xa83453C7fB2D22EbA5d87080C76Ba8fb810349f5


web3swift docs

Celo docs


Project consist of two components the App and Smart contract.

Smart Contract

The smart contract has a DAO style architecture allowing groups, proposals and voting to take place and managed. This contract can easily be extended and is a good starting point.

Crypta iOS

The app has a simplistic design that can be broken down into three sections services, contract and views.

  • Services: async methods and variables that piggy back on the web3swift library.

  • Contract: variables that make up the contract, network and wallet.

  • Views: swiftUI views and viewModels that make up the UI

    ├── Contract
    │   ├── ABI
    │   ├── Methods
    │   ├── Tokens
    │   ├── Network
    │   ├── Address
    │   ├── Wallet
    ├── Services
    │   ├── Web3Services
    │   ├── Web3Errors
    │   ├── KeyStoreServices
    ├── Views
        ├── ...


The most important class within services is Web3Services. This class contains async function used to read and write data from the contract. Also initializes the web3 object to facilitate network settings and keystoreManager.

// Crypta2.0/Services/Web3Services.swift
func readContractMethod(method:ContractMethods,params:[AnyObject],completion:@escaping(Result<[String:Any],Web3Error>) -> Void) {{ [unowned self] in

            let walletAddress = EthereumAddress(cryptaWallet.address)
            let contractAddress = EthereumAddress(contractAddress)
            let contractMethod = method.rawValue

            let extraData: Data = Data() // Extra data for contract method
            let contract = w3.contract(contractABI, at: contractAddress, abiVersion: abiVersion)!

            var options = TransactionOptions.defaultOptions

            options.from = walletAddress
            options.gasPrice = .automatic
            options.gasLimit = .automatic

            let tx =, parameters: params, extraData: extraData, transactionOptions: options)!

            let result = try

        }catch {
            completion(.failure(error as! Web3Error))


Primarily consisting of files with hard coded strings used as building boxes that make up the contract. The most complex seems to be the contract ABI.


The abi allows another program to interact with the contract. Basically a list of all the variables and functions, inputs and outputs that the contract has available. The app needs this to communicate with the contract. The ABI below was copied from the DAO.json file that Truffle created in the build folder.

// Crypta2.0/Contract/ABI.swift
// MARK: contractABI
let contractABI =
      "anonymous": false,
      "inputs": [
          "indexed": false,
          "internalType": "uint256",
          "name": "",
          "type": "uint256"
      "name": "GroupActivated",
      "type": "event"

Contract Address

When migrating a contract to a network was successful, it will output the contract address. This address is needed within the app.

// Crypta2.0/Contract/Address.swift
// DAO contract address uploaded to testnet
let contractAddress = "0xa83453C7fB2D22EbA5d87080C76Ba8fb810349f5"

App Pic

Async Calls

Sending a async call from views can get messy. Here are couple different ways to that.


Easy and simple, but only works with swiftUI 15.0+ Check out the Apple docs on .task

// Crypta2.0/Views/BalanceView.swift
.task {

            Web3Services.shared.getTokenBalance(token: token) { result in
                case .success(let value):
                    balance = value
                case .failure(let error):
                    self.error = CryptaError(description: error.localizedDescription)


More complex, but works with order versions and storyboard.

// Crypta2.0/Views/ProposalViewModel.swift
func createProposal(groupId:BigUInt,proposal:Proposal,choiceOne:String,choiceTwo:String ,password:String, completion:@escaping(TransactionSendingResult) -> Void){
    showProgress = true
    // create params for contract method
    let startTime = Int(proposal.proposalStart)
    let endTime = Int(proposal.proposalEnd)
    let params = [groupId,proposal.title,proposal.description,startTime,endTime,[[0,choiceOne],[0,choiceTwo]]] as [AnyObject]
    // Make call with shared instance
    Web3Services.shared.writeContractMethod(method: .createProposal, params: params, password:password ) {
        result in
        // Update UI on main thread
        DispatchQueue.main.async { [unowned self] in
            showProgress = false
            switch(result) {
            case .success(let tx):
                // Tx was success, save new proposal and add to proposals
                var proposal = proposal

       = BigUInt(proposals.count)

       = Vote(hasVoted: false, indexChoice: BigUInt(0))
            case .failure(let txError):
                self.error = CryptaError(description: txError.errorDescription)

// Crypta2.0/Views/ProposalView.swift

Button("Create Proposal") {
  contentVM.sendingWriteTx = true
   contentVM.popOverProposal = false

   // Call and wait for successful tx
   // Error is handled back in view model
   proposalVM.createProposal(groupId:!, proposal: newProposal, choiceOne: choiceOne, choiceTwo: choiceTwo, password: password) { success in
       // reset proposal object
       newProposal = Proposal()
       choiceOne = ""
       choiceTwo = ""

       selectedGroup.proposalCount! += 1
       // Get ready to show tx
       contentVM.txToShow = success
       contentVM.showPopOverForTx = true
       contentVM.sendingWriteTx = false


? Licence

The project is available under MIT licence


View Github