2. Manage the default payment application

The default payment application is launched when the end user performs a double-click or field-detect action.

The double-click payment experience can be enabled or disabled by the end user.

End-user settings for the default payment application

If your application receives the NFC launch events below when the end user performs a double-click or field-detect action, it indicates that your payment application is set as the default payment application.

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
        
    // to support initiate contactless payments by double-click or field-detect action 
    // when application is not running + application is the default payment application
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        
        if #available(iOS 17.4, *) {
            if let nfcEvent = connectionOptions.nfcEvent {
                switch nfcEvent {
                case .presentation:
                    // use case for double-click
                    break
                case .readerDetected:
                    // use case for field-detect
                    break
                @unknown default: break
                }
            }
        }
    }

}


extension SceneDelegate: NFCWindowSceneDelegate {
    @available(iOS 17.4, *)
    // to support initiate contactless payments by double-click or field-detect action when application is background or foreground and is the default payment application
    func windowScene(_ windowScene: UIWindowScene, didReceiveNFCWindowSceneEvent event: NFCWindowSceneEvent) {
        switch event {
        case .presentation:
            // use case for double-click
            break
        case .readerDetected:
            // use case for field-detect
            break
        @unknown default: break
        }
    }
}

You can still perform a contactless payment when the application is not set as the default payment application. However, a double-click or field-detect action may bring the default application to the foreground.