Upload metadata to IPFS

follow the instruction to install IPFS on your machine.

Run your own IPFS node:

ipfs daemon

Open a new tab, goto the directory where the NFT image (example.jpg) is located, upload it to IPFS:

ipfs add example.jpg

Terminal will output something like:

added QmcoxJV7ypCFDPhjiHUxeUw4g9Sy6uULiJKrgpFphh6jbG example.jpg

Create a metadata file (metadata.json) with the NFT's information and the image hash from last step (QmcoxJV7ypCFDPhjiHUxeUw4g9Sy6uULiJKrgpFphh6jbG):

{
    "title": "Asset Metadata",
    "type": "object",
    "properties": {
        "name": {
            "type": "string",
            "description": "Demo NFT"
        },
        "description": {
            "type": "string",
            "description": "This NFT is created for demonstration"
        },
        "author" : {
            "type": "string",
            "description":"Cortex"
        },
        "image": {
            "type": "string",
            "description": "https://ipfs.io/ipfs/QmcoxJV7ypCFDPhjiHUxeUw4g9Sy6uULiJKrgpFphh6jbG"
        }
    }
}

Upload the metadata to IPFS:

ipfs add metadata.json

You will get the hash for this file (QmbLJJHKFNmvwFq475iYCCAw8vvBwhRqSqLgEVztmpUDAr).

The NFT token contract

The NFT smart contract file (Artwork.sol) is created for you under the contracts directory:

pragma solidity ^0.4.24;

import "./CRC4/CRC4Full.sol";
import "./utils/Counters.sol";
import "./utils/Ownable.sol";

contract Artwork is CRC4Full, Ownable {
    using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    constructor(string memory _name, string memory _symbol) 
        CRC4Full(_name, _symbol) public 
    {}

    function addItem(address _owner, string memory _tokenURI) public onlyOwner returns (uint256) {
        _tokenIds.increment();

        uint256 newItemId = _tokenIds.current();
        _mint(_owner, newItemId);
        _setTokenURI(newItemId, _tokenURI);

        return newItemId;
    }
}

Deploy to the blockchain

Note: deploying smart contract through Remix require you to have Cortex wallet extension installed on Chrome browser, also make sure you have enough CTXC for paying the endorphin fees.

Goto https://cerebro.cortexlabs.ai/remix, click on the Solidity environment

Then select the File Explorers icon

Adding our smart contract file Artwork.sol and all the files it is inherited from can be troublesome. To simply this process, we have created a flatten version of Artwork.sol in this repository, named Artwork_flat.sol, download or copy this file then add it to Remix.

Select the Solidity Compiler icon then click Compile Arwork_flat.sol

Select the Deploy and run transactions icon, make sure you have the right environment and contract selected

Extend the deployment box by clicking on the little downward arrow on the right

Type in the name and the symbol for your NFT token, for example, My First NFT (MFN). Click on the transact button to deploy the contract to the blockchain:

A window will pop up asking for confirmation, click confirm

Mint the artwork

You will be able to see the deployed contract after successfully deploying it to the network. Click on the little arrow on the left to expend the content

Find the addItem function

put your wallet address as the owner. The format for tokenURI:

https://ipfs.io/ipfs/[metadata_hash]

e.g. for previous metadata.json file in this guide, https://ipfs.io/ipfs/QmbLJJHKFNmvwFq475iYCCAw8vvBwhRqSqLgEVztmpUDAr Again, like deploying the contract, click on transact to send the transaction.

When the transaction is confirmed, you now have successfully created your first NFT on Cortex blockchain, you can find your CRC4 token on Cerebro explorer. You can also view your NFT collections through our wallet APP for iOS or android.