NFTs (BTC-721)

The BTC-721 token standard on Bitcoin is similar to ERC-721 on Ethereum. It can represent virtually anything in Bitcoin:

• collectible items

• memberships

• lottery tickets

• in-game items

• and more

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Write a BTC-721 smart contract

Extending the OpenZeppelin ERC-721 contract, we can create a hypothetical PFP NFT collection (CryptoWizards) on Bitcoin

// SPDX-License-Identifier: 
MITpragma solidity ^0.8.0;​import 
"@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";contract CryptoWizards 
is ERC721URIStorage {constructor() ERC721("CryptoCollections", "Col") 
{}​function safeMint(address to, uint256 tokenId, string memory uri) 
public {_safeMint(to, tokenId);_setTokenURI(tokenId, uri);}}​

Compile the contracts

To compile your contracts, use the built-in hardhat compile task.cd smart-contract-examplesnpm installnpx hardhat compile​

Deploy the contracts

Review config file hardhat.config.ts. The network configs should look like this.networks:

 {mynw: {url: "http://localhost:10002",accounts: {mnemonic: "<your mnemonic with funds>"},timeout: 100_000,},blockscoutVerify: {blockscoutURL: "http://localhost:4000", // your explorer URL...}}Run the deploy scripts using hardhat-deploy.npx hardhat deploy --tags NFTMake sure the accounts in hardhat.config.ts 
 

Interact with the contracts

Once the contracts are deployed, you can interact with them. We've prepared a few hardhat tasks to make it easy for you to interact with the contracts.#

./CryptoCollection/Collection100.jpgnpx 
hardhat mint-nft --metadata wizard100.json --tokenid 100​# output should contain the URInpx hardhat get-nft --uri bfs://2203/0xbe86c97c2ef568d26e3524f54dc2202324092ffd/0xd4b1932Dff95a39c6024428454a3040F5e727980/100​