When to use categories and when to use subclassing? [closed]

Answer 1

• Do you want to change something which happens as part of framework calls during the lifecycle of a UI object? Use Subclass. Override respective methods, such as init, drawrect, layoutsubviews etc.

• Do you want something application wide, something which is in
  addition to the existing functionality, and you don't care if this
  becomes available to all instances of this pre-existing instances of the framework class? Use categories. Example: animate UILabel upon certain user action, and apply this animation through out your app to all UILabel instances.