Adding Klarna payments to your application is as easy as adding a view and performing a few operations on it. You can read more about the flow here.

This guide will teach you how to:

• Render a Payment View
• Operate the payment method via its Payment View.

A Payment View in iOS is called a KlarnaPaymentView. Rendering a payment view consists of creating an instance of the view, passing it an event listener and, adding it to your view hierarchy.

You can initialize the KlarnaPaymentView by providing a return URL and the event listener.

// Create the view
let paymentView = KlarnaPaymentView(category: "klarna", eventListener: self)

// Add as subview
paymentView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(paymentView)

// Create a height constraint that we'll update as its height changes.
self.heightConstr = paymentView.heightAnchor.constraint(equalToConstant: 0)
heightConstr.isActive = true

The SDK will notify you of events via an event listener that you’ll need to implement. It acts like a conventional delegate on iOS, however, unlike a delegate, it’s not optional.

The payment view does not define any height internally. This is because we want to allow you to handle height changes in whichever way is most convenient to you.

The payment view instead notifies you through the event listener you provide it.

func klarnaResized(paymentView: KlarnaPaymentView, to newHeight: CGFloat) {
    self.heightConstr.constant = newHeight
}

We expose six methods on the payment view that you can use to interact with the payment method it’s presenting

Before content is rendered into a payment view, it needs to be configured. You can do this by initializing the view.

After the view has been added and set up, you’ll need to call initialize() with the clientToken you received from the back-end and a returnURL.

paymentView.initialize(clientToken: clientToken, returnUrl: returnUrl)

If successful, klarnaInitialized() will be called in the listener you supplied. If it’s not successful klarnaFailed() will be called instead.

func klarnaInitialized(paymentView: KlarnaPaymentView) {
    paymentView.load()
}

Once you’ve initialized the view and you’re ready to display the KlarnaPaymentView.

Simply call load(), supplying an optional string with updated order data to update the session. This string should be formatted as valid JSON.

paymentView.load()

If successful, klarnaLoaded() will be called in your listener. If anything went wrong, klarnaFailed() will be called. If you’ve loaded several views, you should keep track of which view your user selected to know what to authorize in the next step.

func klarnaLoaded(paymentView: KlarnaPaymentView) {
    // Content has finished loading and if you have any loader you could hide it here.
}

When the payment view is loaded, and the user has confirmed that they want to pay with Klarna it’s time to authorize the session.

When you are ready to authorize the session, call authorize(). As with load, you can supply an optional string to update the session. You can also specify whether auto-finalization should be turned off; if it is, the user may need to be prompted a second time to input data.

paymentView.authorize()

If successful, klarnaAuthorized() will be called in your listener. If not, klarnaFailed() will be called.

func klarnaAuthorized(paymentView: KlarnaPaymentView, approved: Bool, authToken: String?, finalizeRequired: Bool) {
    if approved == true {
        // the authorization was successful
    } else {
        // user is not approved or might require finalization
    }

    if let token = authToken {
        // authorization is successful, backend may create order
    }

There are cases when you might want to allow your customer to change their order after it has been authorized (e.g. in some form of order/summary view). In these cases, if the order or customer details have changed, you’ll need to reauthorize the session.

paymentView.reauthorize()

If successful, klarnaReauthorized() will be called, and if not, klarnaFailed() will be called instead.

func klarnaReauthorized(paymentView: KlarnaPaymentView, approved: Bool, authToken: String?) {
    if approved == true {
        // the reauthorization was successful
    } else {
        // user is not approved or might require finalization
    }

    if let token = authToken {
        // reauthorization is successful, backend may create order
    }

If the session needs to be finalized, you’ll need to perform this last step to get an authorization token.

Call finalise() in order to get the token.

paymentView.finalise()

If successful, klarnaFinalized() will be called in your listener. If not successful, klarnaFailed() will be called.

func klarnaFinalized(paymentView: KlarnaPaymentView, approved: Bool, authToken: String?) {
    if approved == true {
        // the finalization was successful
    } else {
        // user is not approved or might require finalization
    }

    if let token = authToken {
        // finalization is successful, backend may create order
    }

If you’d like to allow the user to review their payment after it’s authorized, this can be done in two ways:

1. Render it in a new view:
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2. Render it in the existing payment view:
   undefined

This will load/replace the view’s content with a description of how your customer will have to perform payment.

paymentView.loadPaymentReview()

If successful klarnaLoadedPaymentReview() will be called in your listener. If not, klarnaFailed() will be called instead.

func klarnaLoadedPaymentReview(paymentView: KlarnaPaymentView) {
    // Payment review loaded
}

This will handle all the errors from the previous implementations. KlarnaPaymentError will contain the information needed to show to the user and also to handle all the states of the listener.

func klarnaFailed(inPaymentView paymentView: KlarnaPaymentView, withError error: KlarnaPaymentError) {
    // handle error
}