(ios): allow to set "preferredContentMode"

README.md

@@ -168,6 +168,16 @@ At the moment the only supported target in OSX is `_system`.
 
 `_blank` and `_self` targets are not yet implemented and are ignored silently. Pull requests and patches to get these to work are greatly appreciated.
 
+### iOS Quirks
+
+Since iOS 13 iPads try to adapt their content mode / user agent for the optimal browsing experience. This may result in iPads having their user agent set to `Macintosh`. You can change this with the `PreferredContentMode` preference in "config.xml".
+
+```xml
+<preference name="PreferredContentMode" value="mobile" />
+```
+
+The example above forces the user agent to contain `iPad`. The other option is to use the value `desktop` to turn the user agent to `Macintosh`.
+
 ### Browser Quirks
 
 - Plugin is implemented via iframe,

src/ios/CDVWKInAppBrowser.m

@@ -758,6 +758,15 @@ - (void)createViews
         configuration.mediaPlaybackRequiresUserAction = _browserOptions.mediaplaybackrequiresuseraction;
     }
 
+    if (@available(iOS 13.0, *)) {
+        NSString *contentMode = [self settingForKey:@"PreferredContentMode"];
+        if ([contentMode  isEqual: @"mobile"]) {
+            configuration.defaultWebpagePreferences.preferredContentMode = WKContentModeMobile;
+        } else if ([contentMode  isEqual: @"desktop"]) {
+            configuration.defaultWebpagePreferences.preferredContentMode = WKContentModeDesktop;
+        }
+
+    }
 
 
     self.webView = [[WKWebView alloc] initWithFrame:webViewBounds configuration:configuration];