1. 检查您的工程是否包含了Adyen Drop In SDK。

2. 如果您的工程已经包含了Adyen Drop In SDK，请检查您的代码是否正确引用了SDK。 例如，在您的 Podfile 中添加以下内容：

pod 'Adyen', '~> 3.5.0'

然后运行pod install以安装新的 SDK。

3. 检查您的代码是否正确初始化了Adyen Drop In。

例如，以下代码展示了如何初始化Adyen Drop In：

class ViewController: UIViewController, DropInComponentDelegate {
    
    var dropInComponent: DropInComponent!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let configuration = DropInComponent.PaymentMethodsConfiguration()
        configuration.card.publicKey = "YOUR_PUBLIC_KEY"
        
        dropInComponent = DropInComponent(paymentMethodsConfiguration: configuration)
        dropInComponent.delegate = self
        
        addChild(dropInComponent)
        view.addSubview(dropInComponent.view)
        dropInComponent.didMove(toParent: self)
    }
    
    func didSubmit(_ data: PaymentComponentData, from component: DropInComponent) {
        // Handle the payment result
    }
    
    func didProvide(_ data: ActionComponentData, from component: DropInComponent) {
        // Handle action data requests, such as 3D Secure authentication
    }
    
    func didFail(with error: Error, from component: DropInComponent) {
        // Handle error
    }
    
}

注意：要正确使用Adyen Drop In，您需要在Adyen网站上注册并获取公钥。