The LoyaltyLion SDK can emit various events, which can be subscribed to when you initialize the WebView.

Listening to these events is typically not required for a basic WebView setup, but is often used to support advanced features

You should only subscribe to events that you intend to handle. The LoyaltyLion SDK checks which handlers have been registered and uses that to conditionally enable functionality.

For example, free product rewards will only be redeemable if the appropriate events (addCartLine, etc) have been registered.

​
Listening to events

The events themselves are the same for both iOS and Android, so the only difference is how to subscribe to them.

On iOS, we emit events using the WKScriptMessageHandler interface. Use your WKUserContentController to subscribe to the events you’re interested in.

class ViewController: UIViewController, WKScriptMessageHandler {
  override func viewDidLoad() {
    let contentController = WKUserContentController()

    contentController.add(self, name: "sdkReady")
  }

  func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
    if message.name == "sdkReady" {
      print("LoyaltyLion SDK is ready")
    }
  }
}

​
sdkReady

This event is emitted once the LoyaltyLion SDK has finished loading. At this point, the WebView JS API can be used to interact with the LoyaltyLion SDK running within the WebView.

​
Example

if message.name == "sdkReady" {
  print("LoyaltyLion SDK is ready")
}

​
addCartLine

This event is emitted when a shopper has redeemed a free product reward, and we need a new line to be added to the cart for the product.

The product data will contain a hidden attribute that our Shopify Function will pick up and automatically apply a discount to the item.

The message body will be an object containing the merchandise ID, quantity and attributes that should be added to the cart via a cartLinesAdd mutation.

​
Message body

​
merchandiseId
string
required

The ProductVariant ID to add to the cart.

Example: gid://shopify/ProductVariant/1001

​
productId
string
required

The Product ID to add to the cart.

Example: gid://shopify/Product/100

​
quantity
number
required

The quantity of the item to add.

​
attributes
object
required

An object containing attributes that should be included with the merchandise line.

Example:

{
  "__lion_sfp_id": "19fdf4cb"
}

​
Example

The message body will be automatically parsed, so they can be typecast to retrieve the values.

if message.name == "addCartLine" {
  if let body = message.body as? [String: Any],
    let merchandiseId = body["merchandiseId"] as? String,
    let quantity = body["quantity"] as? Int,
    let attributes = body["attributes"] as? [String: Any] {

    print("Adding cart line: \(merchandiseId), quantity: \(quantity)")

    // add to Shopify cart
  } else {
    print("Invalid message:", message.body)
  }
}

​
removeCartLine

This event is emitted when we need to remove a line from the cart. This typically occurs when the shopper cancels a previously-redeemed free product reward.

The message body will be an object containing the lineId that should be removed from the cart via a cartLinesRemove mutation.

​
Message body

​
lineId
string
required

The CartLine ID to remove from the cart.

Example: gid://shopify/CartLine/19fdf4cb-5495-4c2f-83d0-40c6a4898f5e

​
merchandiseId
string
required

The ProductVariant ID of the CartLine that is being removed from the cart.

Example: gid://shopify/ProductVariant/1001

​
productId
string
required

The Product ID of the CartLine that is being removed from the cart.

Example: gid://shopify/Product/100

​
Example

The message body will be automatically parsed, so they can be typecast to retrieve the values.

if message.name == "removeCartLine" {
  if let body = message.body as? [String: Any],
    let lineId = body["lineId"] as? String {

    print("Removing cart line: \(lineId)")

    // remove from Shopify cart
  } else {
    print("Invalid message:", message.body)
  }
}