In Objective-C, there is an alternative to subclassing that might be what you want here: associating objects.
It works like this: you can "attach" (associate) an object to another object with a custom key and later retrieve it. So in your case, you would do something like:
#include <objc/runtime.h>
// Top level of your .m file. The type and content of this
// variable don't matter much, we need the _address_ of it.
// See the first link of this answer for details.
static char kDelegateKey = 'd';
- (void)requestDataWith:(NSString *)token
id:(NSString *)id
sender:(id<RequestFactoryDelegate>)sender
{
NSMutableURLRequest *request = //create the request here
NSURLSessionDataTask *dataTask = [self.defaultSession dataTaskWithRequest:request];
// Associate the sender with the dataTask. We use "assign" here
// to avoid retain cycles as per the delegate pattern in Obj-C.
objc_setAssociatedObject(dataTask, &kDelegateKey, sender, OBJC_ASSOCIATION_ASSIGN);
[dataTask resume];
}
- (void)someOtherMethodWithDataTask:(NSURLSessionDataTask *)dataTask
{
// Read the attached delegate.
id<RequestFactoryDelegate> delegate = objc_getAssociatedObject(dataTask, &kDelegateKey);
// Do something with the delegate.
}