title: WKWebview file downloading from blob url
body: <p>For an iOS project I need to download a file, from a webview that gives me a blob URL.
  I've handled this case for iOS 14.5- versions by injecting JavaScript inside the webview and catching the data with the <strong>WKScriptMessageHandler</strong>.
  For iOS 14.5+ versions, i'm using the new <strong>WKDownloadDelegate</strong> because it seems that apple is blocking any file download from a JavaScript injection. Everything is working well under Xcode 12.5 but surprisingly it's not building under Xcode 13.</p>
  <p>I've seen that WKDownloadDelegate methods' have the <strong>@available(iOS 14.5, *)</strong> under Xcode 12.5 but these same methods have the <strong>@available(iOS 15.0, *)</strong> under Xcode 13 :</p>
  <p>Xcode 12.5 :</p>
  <pre><code>@available(iOS 14.5, *)
  func download(_ download: WKDownload, decideDestinationUsing response: URLResponse, suggestedFilename: String, completionHandler: @escaping (URL?) -&gt; Void) 
  
  @available(iOS 14.5, *)
  optional func downloadDidFinish(_ download: WKDownload)
  </code></pre>
  <p>Xcode 13 :</p>
  <pre><code>@available(iOS 15.0, *)
  func download(_ download: WKDownload, decideDestinationUsing response: URLResponse, suggestedFilename: String, completionHandler: @escaping (URL?) -&gt; Void)
  
  @available(iOS 15.0, *)
  optional func downloadDidFinish(_ download: WKDownload)
  </code></pre>
  <p>As i mentioned above, <strong>everything is working on Xcode 12.5</strong>. But for continuous integration purpose, i need it to be working under Xcode 13.</p>
  <p>So my question is : knowing that Apple is blocking any data downloading from a javascript injection for iOS 14.5+ version, and <strong>WKDownloadDelegate</strong> is working under Xcode 13 just for iOS 15+ versions, is there any solution to download a file from a webview for iOS versions between 14.5 and 15.0 under Xcode 13 ?</p>