public protocol ImageDownloadRequestModifier
Represents and wraps a method for modifying request before an image download request starts.
A method will be called just before the
requestbeing sent. This is the last chance you can modify the image download request. You can modify the request for some customizing purpose, such as adding auth token to the header, do basic HTTP auth or something like url mapping.
Usually, you pass an
ImageDownloadRequestModifieras the associated value of
KingfisherOptionsInfoItem.requestModifierand use it as the
optionsparameter in related methods.
If you do nothing with the input
requestand return it as is, a downloading process will start with it.
func modified(for request: URLRequest) -> URLRequest?
The input request contains necessary information like
url. This request is generated according to your resource url as a GET request.
A modified version of request, which you wish to use for downloading an image. If
.emptyRequestas its reason will occur.