solidity | 合约 approval

如果想要通过合约进行交易，那么，首先应该将合约的 token 使用权限，赋给 dex 。

直接上合约。

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

// 合约调用 pancakeswap
// 合约转出任意代币

interface functionContract {
    function allowance(address owner, address spender) external view returns (uint);
    function approve(address spender, uint value) external returns (bool);
}


contract MultiTrade {

    constructor() {
    }

    function getSelfApprovalAmount(address t,address b) view public returns (uint){
        functionContract token = functionContract(t);
        return token.allowance(address(this),b);
    }

    function getApprovalAmount(address t,address a,address b) view public returns (uint){
        functionContract token = functionContract(t);
        return token.allowance(a,b);
    }

    function setApproval(address token,address swapAddress) public{
        functionContract tokenContract = functionContract(token);
        if(tokenContract.allowance(address(this),swapAddress) == 0){
                tokenContract.approve(swapAddress,type(uint256).max);
            }
    }
}