Working With Large Bridge

If you plan to have a large bridge for using a particular Pure Swift Package, like Stripe, working with an editor without code completion can be difficult.

The solution is to work with a local package you will add to your plugin configuration.

The big advantage is that you can test your code before adding it to your KMP project.

Create A Local Package

• From command line : swift package init --name YouPackageName
• From Xcode : File -> New -> Package -> Library

Choose Your Editor

You can either use Xcode or VSCode with the Swift Plugin; both are fine.

Package Manifest

A Swift Package is based on a Manifest, the Package.swift (official documentation)

Example

Package.swift

// swift-tools-version: 5.9
// The swift-tools-version declares the minimum version of Swift required to build this package.

import PackageDescription

let package = Package(
    name: "MyStripeSDK",
    platforms: [.iOS(.v14)],
    products: [
        // Products define the executables and libraries a package produces, making them visible to other packages.
        .library(
            name: "MyStripeSDK",
            targets: ["MyStripeSDK"]),
    ],
    dependencies: [
        .package(url: "https://github.com/stripe/stripe-ios-spm", .upToNextMajor(from: "24.5.0")),
    ],
    targets: [
        // Targets are the basic building blocks of a package, defining a module or a test suite.
        // Targets can depend on other targets in this package and products from dependencies.
        .target(
            name: "MyStripeSDK",
            dependencies: [
                .product(name: "Stripe", package: "stripe-ios-spm"),
                .product(name: "StripePaymentSheet", package: "stripe-ios-spm")
            ]),
        .testTarget(
            name: "MyStripeSDKTests",
            dependencies: [
                "MyStripeSDK"
            ]
        ),
    ]
)

Package Source

Usually located at Sources/[packageName], it has the same requirement as the plugin's bridge source files.

Make your Swift code compatible with Kotlin.

Your Swift code needs to be marked as @objc/@objcMembers and the visibility set as public or it won't be exported and available from your Kotlin code.

Example

Sources/MyStripeSDK/Package.swift

import StripePaymentSheet

@objcMembers public class MyStripeSDK: NSObject {

    private var paymentSheet: PaymentSheet?
    private var paymentIntentClientSecret: String
    private let backendCheckoutUrl = URL(string: "Your backend endpoint/payment-sheet")

    public init(paymentIntentClientSecret: String) {
        self.paymentIntentClientSecret = paymentIntentClientSecret
    }

    public func doStripeJob() {
        var configuration = PaymentSheet.Configuration()
        configuration.merchantDisplayName = "Example, Inc."
        self.paymentSheet = PaymentSheet(paymentIntentClientSecret: self.paymentIntentClientSecret,
                                         configuration: configuration)
    }
}

Plugin Configuration

Add your local package to your plugin configuration, follow the guide.

Example

build.gradle.kts

swiftPackageConfig {
    create("MyStripeSDKLibs") {
        dependency {
            localPackage(
                // absolute path to your Local Package
                path = "$projectDir/../MyStripeSDK",
                packageName = "MyStripeSDK",
                products = {
                    // Export to Kotlin for use in shared Kotlin code, false by default
                    add("MyStripeSDK", exportToKotlin = true)
                }
            )
        }
    }
}

Don't Store Sensitive Data

The local package source is visible

If you share this package, don't put sensitive data inside, as it needs to be added to the Xcode project.

You can use the default plugin's bridge if needed, as it's not visible from the application or your shared Kotlin library.