# iOS Integration

This page provides instructions for integrating Kustom Checkout into an iOS application.

## Before you start

This guide assumes Kustom Checkout has already been set up and is available at a specified API endpoint. For detailed setup, refer to the general Kustom Checkout Integration guide.

## Setup your app

### Import the SDK

#### Swift Package Manager

In Xcode, navigate to File → Swift Packages → Add Package Dependency and enter the repository URL: https://github.com/Kustom-Checkout/kustom-mobile-sdk-spm

In Version, Select Up to Next Major and take the default option. Then choose KustomMobileSDK in the Package Product column.

#### Cocoapods

If you’re using Cocoapods, you can add the SDK by adding the dependency to your Podfile:


```
pod "KustomMobileSDK"
```

Followed by performing:


```bash
pod install
```

You should then be able to import the KustomMobileSDK module in your workspace.

## Working with the Mobile SDK

### Adding Kustom Checkout to your app

The Checkout View in iOS is called `KustomCheckoutView`.

### Creating the View from Code

Create the `KustomCheckoutView` instance in your view controller.  Initialize the view using the `returnURL` and `eventHandler` parameters.


```swift
var checkoutView: KustomCheckoutView?
override func viewDidLoad() {
    super.viewDidLoad()
    checkoutView = KustomCheckoutView(returnURL: URL(`app-schema://`), eventHandler: KustomEventHandler)
}
```

### Initialize SDK with the Checkout snippet

Initialize the `KustomCheckoutView` with the Checkout HTML snippet fetched from your server at `YOUR-URL`.


```swift
checkoutView?.setSnippet(snippet)
```

### Configure Event Listeners

The SDK notifies you of events and errors via a handler object. Implement the `KustomEventHandler` protocol.


```swift
// In case the handler needs to be updated to another reference
checkoutView?.eventHandler = handlerObject // must implement the KustomEventHandler protocol
```

The `KustomEventHandler` protocol exposes methods for handling various events:


```swift
func kustomComponent(_ kustomComponent: KustomComponent, dispatchedEvent event: KustomProductEvent) {
// A few examples of dispatched events shown later in the docs
}
```

and


```swift
func kustomComponent(_ kustomComponent: KustomComponent, encounteredError error: KustomMobileSDKError) {
// Errors related to the sdk
}
```

### Configure Sizing Delegate

The `sizingDelegate` is used to handle resizing of views within the `KustomCheckoutView`.  Implement the `KustomSizingDelegate` protocol.


```swift
checkoutView?.sizingDelegate = listenerObject // must implement the KustomSizingDelegate protocol
```

### Suspend and Resume Checkout

The `suspend()` and `resume()` actions control user interaction with the `KustomCheckoutView`.


```swift
checkoutView?.suspend()
```


```swift
checkoutView?.resume()
```

### Handling External Payment Methods


```swift
checkoutView?.checkoutOptions.merchantHandlesEPM = true
```

(Set before starting Checkout)

The SDK handles external payment method events.

### Handling Validation Errors


```swift
checkoutView?.checkoutOptions.merchantHandlesValidationErrors = true
```

(Set before starting Checkout)

## Return URL

Third-party applications might require returning to your app.  The SDK uses the provided `returnURL` to manage this process.

**Note:** Bank ID authentication for payments might require manual user return to the app after bank authentication.