Output Port Adapter for Single Point of Configuration in Complex UI

When you have nested and complex UI components with multiple sub-view controllers, passing an optional output port (event handler or delegate) down the tree is cumbersome. There are two straight-forward approaches: The second option is “cleaner”, but for a two or three object component might also feel a bit too much.
How do You Really Mock Objects You Don't Own? You Replace Them with Adapters

How do you test NSURLSession
properly? After all, using it in tests directly will hit the servers; that’s not what you want to do 1000s of times per day. Even if you use a localhost
based server replacement the tests will be slower and potentially error-prone as the server replacement may not be 100% accurate. Anyway – there’s a popular series of posts about that topic. There, you’ll learn how to mock NSURLSession
in your tests. I think the advice is good to move on quickly, but it only shifts the problem slightly out of sight. There are better alternatives.