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Overview

This guide outlines how to integrate and use external cryptocurrency wallets with the ParaSwift SDK. It covers setup, deep-linking protocols, authentication, and transaction signing processes for wallets such as MetaMask.

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Deep Linking

The ParaSwift SDK communicates with other apps via deep linking. To enable deep linking for your application, you’ll need to configure your app appropriately.

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Configure URL Schemes

First, you need to configure your app to handle custom URL schemes:
  1. Open your app’s Info.plist file
  2. Add a new entry for LSApplicationQueriesSchemes as an array
  3. Add the URL schemes of supported wallets as strings to this array
<key>LSApplicationQueriesSchemes</key>
<array>
    <string>metamask</string>
</array>

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Configure URL Types

Next, you need to set up URL Types to handle callbacks from external wallets:
  1. In Xcode, select your app target
  2. Go to “Info” tab
  3. Expand “URL Types”
  4. Click the ”+” button to add a new URL Type
  5. Set the “Identifier” to your app’s bundle identifier
  6. Set the “URL Schemes” to a unique scheme for your app

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MetaMask Connector

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Setup

Create and initialize the MetaMask connector with your app’s configuration: 
import ParaSwift

// Create MetaMask configuration
let bundleId = Bundle.main.bundleIdentifier ?? ""
let metaMaskConfig = MetaMaskConfig(
    appName: "Your App Name",
    appId: bundleId,
    apiVersion: "1.0"
)

// Initialize the connector
let metaMaskConnector = MetaMaskConnector(
    para: paraManager,
    appUrl: "https://\(bundleId)",  // Your app's URL
    config: metaMaskConfig
)
Handle incoming deep links from MetaMask by adding a URL handler in your SwiftUI app: 
@main
struct YourApp: App {
    @StateObject private var metaMaskConnector = MetaMaskConnector(
        para: paraManager,
        appUrl: "https://your-app-url",
        config: metaMaskConfig
    )
    
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(metaMaskConnector)
                .onOpenURL { url in
                    metaMaskConnector.handleURL(url)
                }
        }
    }
}

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Connecting

To connect to MetaMask and retrieve the user’s accounts: 
do {
    try await metaMaskConnector.connect()
    // Access connected accounts via metaMaskConnector.accounts
} catch {
    // Handle connection error
}

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Sign Message

To request a signature for a message from MetaMask: 
guard let account = metaMaskConnector.accounts.first else { return }

do {
    let signature = try await metaMaskConnector.signMessage(
        "Message to sign! Hello World",
        account: account
    )
    // Use the signature
} catch {
    // Handle signing error
}

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Send Transaction

To send a transaction through MetaMask using the standard transaction parameters: 
import Web3Core

guard let account = metaMaskConnector.accounts.first else { return }

do {
    let valueInWei = Web3Core.Utilities.parseToBigUInt("0.001", units: .ether)!
    let gasLimit = Web3Core.Utilities.parseToBigUInt("100000", units: .wei)!
    
    let transaction = EVMTransaction(
        to: "0x13158486860B81Dee9e43Dd0391e61c2F82B577F",
        value: valueInWei,
        gasLimit: gasLimit
    )
    
    let txHash = try await metaMaskConnector.sendTransaction(transaction, account: account)
    // Transaction sent successfully, use txHash
} catch {
    // Handle transaction error
}
Alternatively, you can use a raw transaction dictionary format: 
guard let account = metaMaskConnector.accounts.first else { return }

let transaction: [String: String] = [
    "from": account,
    "to": "0x13158486860B81Dee9e43Dd0391e61c2F82B577F",
    "value": "0x38D7EA4C68000", // 0.001 ETH in wei (hex)
    "gasLimit": "0x186A0" // 100000 in hex
]

do {
    let txHash = try await metaMaskConnector.sendTransaction(
        transaction,
        account: account
    )
    // Transaction sent successfully
} catch {
    // Handle transaction error
}

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Properties

The MetaMask connector provides several useful properties: 
// Check if connected to MetaMask
let isConnected = metaMaskConnector.isConnected

// Get list of connected accounts
let accounts = metaMaskConnector.accounts

// Get current chain ID (e.g., "0x1" for Ethereum mainnet)
let chainId = metaMaskConnector.chainId

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Advanced Configuration

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Customizing MetaMask Connection

You can customize various aspects of the MetaMask connection by modifying the MetaMaskConfig: 
let metaMaskConfig = MetaMaskConfig(
    appName: "Your App Name",
    appId: bundleId,
    apiVersion: "1.0",
    appIcon: "https://yourapp.com/icon.png" // Optional custom icon URL
)

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Working with Different Networks

MetaMask supports multiple networks. You can check the current network and adjust your app’s behavior accordingly: 
switch metaMaskConnector.chainId {
case "0x1":
    // Ethereum Mainnet
case "0x5":
    // Goerli Testnet
case "0x89":
    // Polygon
default:
    // Other network
}