Part 4 - UIView's User Interaction Enabled Property

When the user touches the screen, this is called a "user interaction". For a UIView, this property is defaulted to true. In code this property is userInteractionEnabled.

Observations

• Unchecking this property for a button prevents that button from being touched.
• If a UIView has User Interaction Enabled set to false, touches will still pass through to the views below it.
  Example:
  
  
       A - A UIView with User Interaction Enabled set to false.
       B - A UIButton.
       The button can still be clicked.
• Animations set User Interaction Enabled to false during the animation.
• Setting User Interaction Enabled to false on a parent UIView will disable user interaction on all UIViews within the parent (all subviews).
  Example:
  
  
       The button will not work.

(Xcode 8, Swift 3.0)