Vungle iOS SDK used to support both UIWebView and WKWebView. However, UIWebView won't be supported in iOS 13+. To accommodate this change, Vungle has removed all UIWebView from Vungle iOS SDK v6.4.5 and higher.
Apps that run in iOS 8 and higher use the WKWebView class instead of UIWebView. Additionally, consider setting the WKPreferences property javaScriptEnabled to 'false' if you render files that are not supposed to run JavaScript. For additional details about UIWebView, refer to the Apple Developer forum.