💎 How to create KIP7 tokens
In this section you will see how to build a Unity project using the KIP7 (ERC-20) token standard on Kaia.
Getting Started
Start by creating a new project by following the steps at the section Create a new Unity project. Make sure to install all dependencies to fix all bugs.
Use the WebLogin prefab to enable web3 wallet connection
Under Assets → Web3Unity → Scenes, double-click on WebLogin. This is the prefab used to connect a wallet in a WebGL project.
Go to File → Build Settings → WebGL → Switch Platform
From the same window, click on Add Open Scenes (top right) to add the Login scene as the first scene to appear when we run the project.
From the same window, click on Player Settings → Player → Resolution and Presentation, under WebGL Template, select the one with the same as our Unity version (WebGL 2020 for our case).
Go back to the Unity project. Under Assets, select Scenes and double-click on SampleScene to use it as our second scene (FYI the first one is the login scene).
Go to File → Build Settings → Add Open Scenes. The SampleScene will appear under the WebLogin scene. It means the SampleScene, where we will create the buttons to read and write to the contract, will be the next scene after the WebLogin.
Make sure the WebLogin scene is at the top because the order matters.
Create your Contract
- Open Remix IDE, install the Kaia Remix plugin then paste the code below:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
import "@klaytn/contracts/KIP/token/KIP7/KIP7.sol";
import "@klaytn/contracts/access/Ownable.sol";
contract MyToken is KIP7, Ownable {
constructor() KIP7("Test Token", "TST") {
_mint(msg.sender, 100000 * 10 ** 18);
}
function mintToken(address account, uint256 amount) public onlyOwner {
_safeMint(account, amount);
}
}
- Compile your contract and deploy it to kairos testnet. Get your faucet here.
Create your C# script on Unity
Under Project window, right-click on Scenes, click on Create → C# Script. Use the script below.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using System;
using System.Numerics;
using UnityEngine.UI;
using Newtonsoft.Json;
public class ERC20CUSTOM : MonoBehaviour
{
// set chain: ethereum, polygon, klaytn, etc
string chain = "klaytn";
// set network mainnet, testnet
string network = "testnet";
// wallet address that deployed the contract
private string account = "0x7b9B65d4ee2FD57fC0DcFB3534938D31f63cba65";
// set ABI
private readonly string abi = "[ { \"inputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"constructor\" }, { \"anonymous\": false, \"inputs\": [ { \"indexed\": true, \"internalType\": \"address\", \"name\": \"owner\", \"type\": \"address\" }, { \"indexed\": true, \"internalType\": \"address\", \"name\": \"spender\", \"type\": \"address\" }, { \"indexed\": false, \"internalType\": \"uint256\", \"name\": \"value\", \"type\": \"uint256\" } ], \"name\": \"Approval\", \"type\": \"event\" }, { \"anonymous\": false, \"inputs\": [ { \"indexed\": true, \"internalType\": \"address\", \"name\": \"previousOwner\", \"type\": \"address\" }, { \"indexed\": true, \"internalType\": \"address\", \"name\": \"newOwner\", \"type\": \"address\" } ], \"name\": \"OwnershipTransferred\", \"type\": \"event\" }, { \"anonymous\": false, \"inputs\": [ { \"indexed\": true, \"internalType\": \"address\", \"name\": \"from\", \"type\": \"address\" }, { \"indexed\": true, \"internalType\": \"address\", \"name\": \"to\", \"type\": \"address\" }, { \"indexed\": false, \"internalType\": \"uint256\", \"name\": \"value\", \"type\": \"uint256\" } ], \"name\": \"Transfer\", \"type\": \"event\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"owner\", \"type\": \"address\" }, { \"internalType\": \"address\", \"name\": \"spender\", \"type\": \"address\" } ], \"name\": \"allowance\", \"outputs\": [ { \"internalType\": \"uint256\", \"name\": \"\", \"type\": \"uint256\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"spender\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" } ], \"name\": \"approve\", \"outputs\": [ { \"internalType\": \"bool\", \"name\": \"\", \"type\": \"bool\" } ], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"account\", \"type\": \"address\" } ], \"name\": \"balanceOf\", \"outputs\": [ { \"internalType\": \"uint256\", \"name\": \"\", \"type\": \"uint256\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"name\": \"decimals\", \"outputs\": [ { \"internalType\": \"uint8\", \"name\": \"\", \"type\": \"uint8\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"spender\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"subtractedValue\", \"type\": \"uint256\" } ], \"name\": \"decreaseAllowance\", \"outputs\": [ { \"internalType\": \"bool\", \"name\": \"\", \"type\": \"bool\" } ], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"spender\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"addedValue\", \"type\": \"uint256\" } ], \"name\": \"increaseAllowance\", \"outputs\": [ { \"internalType\": \"bool\", \"name\": \"\", \"type\": \"bool\" } ], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"account\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" } ], \"name\": \"mintToken\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [], \"name\": \"name\", \"outputs\": [ { \"internalType\": \"string\", \"name\": \"\", \"type\": \"string\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"name\": \"owner\", \"outputs\": [ { \"internalType\": \"address\", \"name\": \"\", \"type\": \"address\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"name\": \"renounceOwnership\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"recipient\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" } ], \"name\": \"safeTransfer\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"recipient\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" }, { \"internalType\": \"bytes\", \"name\": \"_data\", \"type\": \"bytes\" } ], \"name\": \"safeTransfer\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"sender\", \"type\": \"address\" }, { \"internalType\": \"address\", \"name\": \"recipient\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" } ], \"name\": \"safeTransferFrom\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"sender\", \"type\": \"address\" }, { \"internalType\": \"address\", \"name\": \"recipient\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" }, { \"internalType\": \"bytes\", \"name\": \"_data\", \"type\": \"bytes\" } ], \"name\": \"safeTransferFrom\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"bytes4\", \"name\": \"interfaceId\", \"type\": \"bytes4\" } ], \"name\": \"supportsInterface\", \"outputs\": [ { \"internalType\": \"bool\", \"name\": \"\", \"type\": \"bool\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"name\": \"symbol\", \"outputs\": [ { \"internalType\": \"string\", \"name\": \"\", \"type\": \"string\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [], \"name\": \"totalSupply\", \"outputs\": [ { \"internalType\": \"uint256\", \"name\": \"\", \"type\": \"uint256\" } ], \"stateMutability\": \"view\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"to\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" } ], \"name\": \"transfer\", \"outputs\": [ { \"internalType\": \"bool\", \"name\": \"\", \"type\": \"bool\" } ], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"from\", \"type\": \"address\" }, { \"internalType\": \"address\", \"name\": \"to\", \"type\": \"address\" }, { \"internalType\": \"uint256\", \"name\": \"amount\", \"type\": \"uint256\" } ], \"name\": \"transferFrom\", \"outputs\": [ { \"internalType\": \"bool\", \"name\": \"\", \"type\": \"bool\" } ], \"stateMutability\": \"nonpayable\", \"type\": \"function\" }, { \"inputs\": [ { \"internalType\": \"address\", \"name\": \"newOwner\", \"type\": \"address\" } ], \"name\": \"transferOwnership\", \"outputs\": [], \"stateMutability\": \"nonpayable\", \"type\": \"function\" } ]";
// set rpc endpoint url
string rpc = "https://public-en-kairos.node.kaia.io";
// set contract address
private string contract = "0xAc88Ee877D1dCf6da3672099FE4618c9d30F0d0B";
// set recipient address
private string toAccount = "0x7AB1b3C8396aDE55F959fB9B2dA43deFDdA23c52";
// set amount to transfer
private string amount = "10000";
// Use this if you want to display the balance of an account
/*public Text balance;
void Start()
{
string account = PlayerPrefs.GetString("Account");
balance.text = account;
}
*/
// call the "name" function
async public void Name()
{
// function name
string method = "name";
// arguments
string args = "[]";
try
{
string response = await EVM.Call(chain, network, contract, abi, method, args,rpc);
Debug.Log("Token name: " + response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// call the "totalSupply" function
async public void TotalSupply()
{
// function name
string method = "totalSupply";
// arguments
string args = "[]";
try
{
string response = await EVM.Call(chain, network, contract, abi, method, args,rpc);
Debug.Log("Total Supply: " + response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// call the "balanceOf" function
async public void BalanceOf()
{
// function name
string method = "balanceOf";
// arguments
string args = "[\"0x7b9B65d4ee2FD57fC0DcFB3534938D31f63cba65\"]";
try
{
string response = await EVM.Call(chain, network, contract, abi, method, args,rpc);
Debug.Log("Balance of 0x7b9B65d4ee2FD57fC0DcFB3534938D31f63cba65: " + response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// call the "transfer" function
async public void Transfer()
{
// function name
string method = "transfer";
// put arguments in an array of string
string[] obj = {toAccount, amount};
// serialize arguments
string args = JsonConvert.SerializeObject(obj);
// value in ston (wei) in a transaction
string value = "0";
// gas limit: REQUIRED
string gasLimit = "1000000";
// gas price: REQUIRED
string gasPrice = "250000000000";
try
{
string response = await Web3GL.SendContract(method, abi, contract, args, value, gasLimit, gasPrice);
Debug.Log(response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// call the "safeTransfer" function
async public void SafeTransfer()
{
string method = "safeTransfer";
string[] obj = {toAccount, amount};
string args = JsonConvert.SerializeObject(obj);
string value = "0";
// gas limit OPTIONAL
string gasLimit = "1000000";
// gas price OPTIONAL
string gasPrice = "250000000000";
try
{
//string response = await Web3GL.SendContract(chain, network, contract, abi, method, args,rpc);
string response = await Web3GL.SendContract(method, abi, contract, args, value, gasLimit, gasPrice);
Debug.Log(response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// call the "mintToken" function
async public void Mint()
{
// recipient
string toAccount = "0x57468012dF29B5f1C4b5baCD1CD2F0e2eC323316";
// amount to send
string amount = "100";
// function name
string method = "mintToken";
// put arguments in an array of string
string[] obj = {toAccount, amount};
// serialize arguments
string args = JsonConvert.SerializeObject(obj);
// value in ston (wei) in a transaction
string value = "0";
// gas limit: REQUIRED
string gasLimit = "1000000";
// gas price: REQUIRED
string gasPrice = "250000000000";
try
{
string response = await Web3GL.SendContract(method, abi, contract, args, value, gasLimit, gasPrice);
Debug.Log(response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// call the "approve" function
async public void Approve()
{
// spender
string spender = "0x57468012dF29B5f1C4b5baCD1CD2F0e2eC323316";
// amount
string amount = "100";
// function name
string method = "approve";
// put arguments in an array of string
string[] obj = {spender, amount};
// serialize arguments
string args = JsonConvert.SerializeObject(obj);
string value = "0";
// gas limit OPTIONAL
string gasLimit = "1000000";
// gas price OPTIONAL
string gasPrice = "250000000000";
try
{
string response = await Web3GL.SendContract(method, abi, contract, args, value, gasLimit, gasPrice);
Debug.Log(response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
}
We will create 7 buttons ( Name, Total Supply, BalanceOf, Transfer, SafeTransfer, Mint and Approve) on the UI to interact with our KIP7 token.
To create the buttons, follow the steps in the section Custom Interaction with Login.
Your UI should look like this:
Link each button to the corresponding function in the contract. E.g here, we linked the button Name to the function Name() in the script, which calls the function name() in the contract.
Change the chainId of the network in the WebGL Templates folder to 1001 to connect to kairos testnet
Click on ▶️ to run the program and test the Name, Total Supply and BalanceOf buttons.
Test the Transfer and the Mint function
To test the Transfer button, we need to build and run the project. So go to File → Build and Run
Click on Login to connect Metamask.
Once connected, click on Transfer to execute the KIP7 token transfer.
Here are the details of the transaction on Kaiascope.
To test the Mint and SafeTransfer function, click on the corresponding button and confirm your transaction on KaiaScan.
If you have any questions, please join our Discord server, or send us an email at developers@kaia.io