Understanding Metamask: A Deeper Dive into Unity Plugin Integration

As a developer working with Unity and MetaMask, you’re probably familiar with the popular decentralized finance (DeFi) platform’s mobile wallet. However, when integrating the MetaMask Unity plugin, you encounter a common problem: the user is shown different Ethereum amounts than what the plugin requested.

The Problem:

In our previous example, we integrated the MetaMask Unity plugin using the provided asset store package and following the documentation. The plugin is designed to show users the correct Ether (ETH) amount for their wallet balance as requested by the platform’s UI. However, in some cases, this value may not match the one you set in your project settings.

The Solution:

To fix this issue, let’s investigate why the MetaMask Unity plugin is showing different amounts than what you specified. The reason lies in the way the plugin interacts with the Ethereum blockchain and wallet balance.

When users interact with their Ethereum accounts, they are not directly interacting with your project’s wallet balance. Instead, it is an external API call that returns a specific amount of ETH that the user can transfer or withdraw from their balance. This is where it gets interesting – the plugin uses this external API to retrieve the correct amount of ETH.

The Unity plugin code:

To better understand how the code works, let’s take a closer look at the Metamask Unity plugin code. We’ll focus on the UnityPlugin class and its OnCoinChanged event handler:

using UnityEngine;
using MetaMask.Unity;
public class UnityPlugin : MonoBehaviour
{
// ... other variables and methods ...
private void OnCoinChanged(Coin coin, ulong value)
{
// Update wallet balance UI with correct ETH amount
WalletBalanceUI.instance.SetWalletBalance(coin.Name, value);
}
}

As you can see, the OnCoinChanged event handler gets the current coin (e.g. Ether) and its corresponding value. It then updates a UI element called WalletBalanceUI to display the correct ETH amount.

Why different amounts are displayed:

The reason for this discrepancy lies in the way the MetaMask Unity Plugin interacts with the Ethereum blockchain. When a user deposits or withdraws funds to their account, MetaMask sends an API request to retrieve the balance data. The plugin then updates the UI element using this API response.

In our case, when we update the WalletBalanceUI instance with the correct amount of ETH, we are actually updating the user’s wallet balance on the Ethereum blockchain. However, the plugin does not automatically send a request to update the wallet balance on your project’s side.

The solution:

To fix this issue, you need to make sure that when displaying the user’s wallet balance on the MetaMask Unity Plugin, you are using the correct amount of ETH as requested by the platform. You can do this by:

• Using a reliable API to retrieve the user’s wallet balance.

• Passing the retrieved value from your project’s side (e.g. in OnCoinChanged) to the plugin.

Here is an updated example code snippet showing how to update the UI element with the correct amount of ETH:

“`csharp

using UnityEngine;

using MetaMask.Unity;

public class WalletBalanceUI : MonoBehaviour

{

private void OnCoinChanged(Coin coin, ulong value)

{

// Update wallet balance UI with correct ETH amount

WalletBalanceDisplay.Instance.SetWalletBalance(coin.Name, value);

}

}

// Example usage in your project’s C

code:

private WalletBalanceDisplay walletBalanceDisplay;

void Start()

{

walletBalanceDisplay = GetComponent();

walletBalanceDisplay.