CSS 样式在iOS上不起作用

链接：https://forums.xamarin.com/discussion/141665/uiwebview-in-xamarin-ios-seems-to-ignore-external-css-styles

因为iOS不允许访问不安全的链接，需要把他们添加到白名单中，具体做法在info.plist中添加如下字段

  <key>NSAppTransportSecurity</key>
  <dict> 
    <key>NSExceptionDomains</key>
    <dict>   
      <key>your domain</key>
      <dict>   
        <key>NSExceptionRequiresForwardSecrecy</key>
        <false/>
        <key>NSExceptionAllowsInsecureHTTPLoads</key>
        <true/>
        <key>NSIncludesSubdomains</key>
        <true/>
      </dict>     
    </dict>
  </dict>