private void AddCustomScheme(string scheme, ResolveWebResourceDelegate requestHandler)
{
// Because of WKWebView limitations, this can only be called during the constructor
// before the first call to Show. To enforce this, it's private and is only called
// in response to the constructor options.
WebResourceRequestedCallback callback = (string url, out int numBytes, out string contentType) =>
{
var responseStream = requestHandler(url, out contentType, out Encoding encoding);
if (responseStream == null)
{
// Webview should pass through request to normal handlers (e.g., network)
// or handle as 404 otherwise
numBytes = 0;
return(default);
private static extern void BlazorWebViewNative_AddCustomScheme(IntPtr blazorWebView, string scheme, WebResourceRequestedCallback requestHandler);
