I was really happy with the power of this inspect ... it's called Sherlock! try it! Fantastic to debbugging view, constraints in real time and simulate sizing etc. on your iOS simulator. Install from here.
it's very important have a clean structure of project. I think that some rules are fundamental to the maintenance of code.
I don't found a simple guide for this. Here a simple swift code for achieve this goal.
You can touch with your hands the powerful of widgets and notification in iOS8