Could not find information. I built pg app with 'cordova-plugin-wkwebview-engine'.
How to check if phonegap web app on ios 9.2 is really using WKWebview? Could not find info how userAgent string should look like for WKWebView.
Previous answer doesn't work on iOS 10, but you can use this code
if (window.webkit) {
//WKWebView
}
Old answer: You can check for indexedDB
if (window.indexedDB) {
//WKWebView
}