У вашего броузера проблема в совместимости с HTML5
Here is how to load a UIImage Asynchronously and set it to a UIImageView in Swift. When loading images from the web, you want to load them asynchronously so they don't make your app hang.
http://www.appdesignvault.com/xcode-swift-tutorial-dribbble/
This is one video in a 6-part Xcode Series. Click the link above to get the complete course