> For the complete documentation index, see [llms.txt](https://docs.dragonswap.app/dragonswap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.dragonswap.app/dragonswap/resources/developer-resources/smart-contracts/dragonswapv2/core/interfaces/callbacks/idragonswapv2swapcallback.md).

# IDragonswapV2SwapCallback

Any contract that calls IDragonswapV2PoolActions#swap must implement this interface

### Functions[​](https://docs.uniswap.org/contracts/v3/reference/core/interfaces/callback/IUniswapV3SwapCallback#functions) <a href="#functions" id="functions"></a>

#### dragonswapV2SwapCallback[​](https://docs.uniswap.org/contracts/v3/reference/core/interfaces/callback/IUniswapV3SwapCallback#uniswapv3swapcallback) <a href="#uniswapv3swapcallback" id="uniswapv3swapcallback"></a>

```solidity
  function dragonswapV2SwapCallback(
    int256 amount0Delta,
    int256 amount1Delta,
    bytes data
  ) external
```

Called to `msg.sender` after executing a swap via IDragonswapV2Pool#swap.

In the implementation you must pay the pool tokens owed for the swap. The caller of this method must be checked to be a DragonswapV2Pool deployed by the canonical DragonswapV2Factory. amount0Delta and amount1Delta can both be 0 if no tokens were swapped.

**Parameters:**[**​**](https://docs.uniswap.org/contracts/v3/reference/core/interfaces/callback/IUniswapV3SwapCallback#parameters)

| Name           | Type   | Description                                                                                                                                                                             |
| -------------- | ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `amount0Delta` | int256 | The amount of token0 that was sent (negative) or must be received (positive) by the pool by the end of the swap. If positive, the callback must send that amount of token0 to the pool. |
| `amount1Delta` | int256 | The amount of token1 that was sent (negative) or must be received (positive) by the pool by the end of the swap. If positive, the callback must send that amount of token1 to the pool. |
| `data`         | bytes  | Any data passed through by the caller via the IDragonswapV2PoolActions#swap call.                                                                                                       |