Just found out today that if a UIViewController subclass is constructed programmatically (that is without using Interface Builder),
and, if we don’t create and assign a UIView inside loadView:
Then, this could ruin the animation transition of
presentViewController:animated:completion:. In other words, the transition animation doesn’t occur.
There’s a reason why the documentation says that we need to implement this. I saw at least one project that doesn’t follow this rule.