👑 How to create KIP17 tokens
In this section you will see how to build a Unity project using the KIP17 (ERC-721) 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 ^0.8.4;
import "@klaytn/contracts/KIP/token/KIP17/KIP17.sol";
import "@klaytn/contracts/KIP/token/KIP17/extensions/KIP17Enumerable.sol";
//import "@klaytn/contracts/access/Ownable.sol;
import "@klaytn/contracts/utils/Counters.sol";
contract HappyMonkey is KIP17, KIP17Enumerable {
using Counters for Counters.Counter;
Counters.Counter private _tokenIdCounter;
uint256 public MINT_PRICE = 0.05 ether;
uint public MAX_SUPPLY = 100;
constructor() KIP17("HappyMonkey", "HM") {
// Start token ID at 1. By default is starts at 0.
_tokenIdCounter.increment();
}
function withdraw() public {
require(address(this).balance > 0, "Balance is zero");
payable(msg.sender).transfer(address(this).balance);
}
function safeMint(address to) public payable {
require(totalSupply() < MAX_SUPPLY, "Can't mint anymore tokens.");
require(msg.value >= MINT_PRICE, "Not enough ether sent.");
uint256 tokenId = _tokenIdCounter.current();
_tokenIdCounter.increment();
_safeMint(to, tokenId);
}
function _baseURI() internal pure override returns (string memory) {
return "ipfs://happyMonkeyBaseURI/";
}
function _beforeTokenTransfer(address from, address to, uint256 tokenId)
internal
override(KIP17, KIP17Enumerable)
{
super._beforeTokenTransfer(from, to, tokenId);
}
// The following functions are overrides required by Solidity.
function supportsInterface(bytes4 interfaceId)
public
view
override(KIP17, KIP17Enumerable)
returns (bool)
{
return super.supportsInterface(interfaceId);
}
}
Find the ERC721 source code here
- 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 KIP17Example : MonoBehaviour
{
// set chain: ethereum, polygon, klaytn, etc
string chain = "klaytn";
// set network mainnet, testnet
string network = "testnet";
// set contract address
private string contract = "0x1625026Eb24A40728dC3c574d10Cf08ee38cBC9A";
// set contract ABI
private readonly string abi = "[{\"inputs\":[{\"internalType\":\"string\",\"name\":\"name\",\"type\":\"string\"},{\"internalType\":\"string\",\"name\":\"symbol\",\"type\":\"string\"}],\"stateMutability\":\"nonpayable\",\"type\":\"constructor\",\"signature\":\"constructor\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"owner\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"approved\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"Approval\",\"type\":\"event\",\"signature\":\"0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"owner\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"operator\",\"type\":\"address\"},{\"indexed\":false,\"internalType\":\"bool\",\"name\":\"approved\",\"type\":\"bool\"}],\"name\":\"ApprovalForAll\",\"type\":\"event\",\"signature\":\"0x17307eab39ab6107e8899845ad3d59bd9653f200f220920489ca2b5937696c31\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"previousOwner\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"newOwner\",\"type\":\"address\"}],\"name\":\"OwnershipTransferred\",\"type\":\"event\",\"signature\":\"0x8be0079c531659141344cd1fd0a4f28419497f9722a3daafe3b4186f6b6457e0\"},{\"anonymous\":false,\"inputs\":[{\"indexed\":true,\"internalType\":\"address\",\"name\":\"from\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"indexed\":true,\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"Transfer\",\"type\":\"event\",\"signature\":\"0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"approve\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0x095ea7b3\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"owner\",\"type\":\"address\"}],\"name\":\"balanceOf\",\"outputs\":[{\"internalType\":\"uint256\",\"name\":\"\",\"type\":\"uint256\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x70a08231\"},{\"inputs\":[{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"getApproved\",\"outputs\":[{\"internalType\":\"address\",\"name\":\"\",\"type\":\"address\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x081812fc\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"owner\",\"type\":\"address\"},{\"internalType\":\"address\",\"name\":\"operator\",\"type\":\"address\"}],\"name\":\"isApprovedForAll\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0xe985e9c5\"},{\"inputs\":[],\"name\":\"name\",\"outputs\":[{\"internalType\":\"string\",\"name\":\"\",\"type\":\"string\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x06fdde03\"},{\"inputs\":[],\"name\":\"owner\",\"outputs\":[{\"internalType\":\"address\",\"name\":\"\",\"type\":\"address\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x8da5cb5b\"},{\"inputs\":[{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"ownerOf\",\"outputs\":[{\"internalType\":\"address\",\"name\":\"\",\"type\":\"address\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x6352211e\"},{\"inputs\":[],\"name\":\"renounceOwnership\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0x715018a6\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"from\",\"type\":\"address\"},{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"safeTransferFrom\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0x42842e0e\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"from\",\"type\":\"address\"},{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"},{\"internalType\":\"bytes\",\"name\":\"_data\",\"type\":\"bytes\"}],\"name\":\"safeTransferFrom\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0xb88d4fde\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"operator\",\"type\":\"address\"},{\"internalType\":\"bool\",\"name\":\"approved\",\"type\":\"bool\"}],\"name\":\"setApprovalForAll\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0xa22cb465\"},{\"inputs\":[{\"internalType\":\"bytes4\",\"name\":\"interfaceId\",\"type\":\"bytes4\"}],\"name\":\"supportsInterface\",\"outputs\":[{\"internalType\":\"bool\",\"name\":\"\",\"type\":\"bool\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x01ffc9a7\"},{\"inputs\":[],\"name\":\"symbol\",\"outputs\":[{\"internalType\":\"string\",\"name\":\"\",\"type\":\"string\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0x95d89b41\"},{\"inputs\":[{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"tokenURI\",\"outputs\":[{\"internalType\":\"string\",\"name\":\"\",\"type\":\"string\"}],\"stateMutability\":\"view\",\"type\":\"function\",\"constant\":true,\"signature\":\"0xc87b56dd\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"from\",\"type\":\"address\"},{\"internalType\":\"address\",\"name\":\"to\",\"type\":\"address\"},{\"internalType\":\"uint256\",\"name\":\"tokenId\",\"type\":\"uint256\"}],\"name\":\"transferFrom\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0x23b872dd\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"newOwner\",\"type\":\"address\"}],\"name\":\"transferOwnership\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0xf2fde38b\"},{\"inputs\":[{\"internalType\":\"string\",\"name\":\"baseURI_\",\"type\":\"string\"}],\"name\":\"setBaseURI\",\"outputs\":[],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0x55f804b3\"},{\"inputs\":[{\"internalType\":\"address\",\"name\":\"recipient\",\"type\":\"address\"},{\"internalType\":\"string\",\"name\":\"tokenURI\",\"type\":\"string\"}],\"name\":\"mintNFT\",\"outputs\":[{\"internalType\":\"uint256\",\"name\":\"\",\"type\":\"uint256\"}],\"stateMutability\":\"nonpayable\",\"type\":\"function\",\"signature\":\"0xeacabe14\"}]";
// set rpc url endpoint
//string rpc = "https://public-node-api.klaytnapi.com/v1/baobab";
// Call the "owner" function with "10" as argument
async public void GetOwner()
{
// function name
string method = "owner";
// arguments
string args = "[]";
try
{
string response = await EVM.Call(chain, network, contract, abi, method, args);
Debug.Log(response);
} catch(Exception e)
{
Debug.LogException(e, this);
}
}
// Call the "safeMint" function
async public void SafeMint()
{
// function name
string method = "safeMint";
// arguments
string args = "[\"0x646268287Aa8A20947d781E845Cb9631A644D1E1\"]";
// value in ston to add in the transaction
string value = "50000000000000000";
// 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 to = "0x57468012dF29B5f1C4b5baCD1CD2F0e2eC323316";
// token ID
string tokenId = "1";
// function name
string method = "approve";
string[] obj = {to, tokenId};
// arguments
string args = JsonConvert.SerializeObject(obj);
// value in ston to add in the transaction
string value = "50000000000000000";
// 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);
}
}
}
Create the buttons
We will create 2 buttons (Owner and Mint) on the UI to interact with our KIP17 token. To create the buttons, follow the steps in the section Custom Interaction with Login.
Build and Run the project
Go to File → Build and Run.
Click on Login to connect Metamask.
Click on Mint and confirm your transaction.
Here are the details of the transaction on Klaytnscope.
If you have any questions, please join our Discord server, or send us an email at developers@kaia.io