title: How does compiler know which function I want to use?
body: <p>I defined two functions.They are all the same, except in different class. And I imported one class into another class, and then used @selector(functionName).How does compiler know which function I want to use?</p>
  <p><a href="https://i.stack.imgur.com/b9khL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/b9khL.png" alt="enter image description here" /></a></p>
  <p><a href="https://i.stack.imgur.com/C1KBj.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/C1KBj.png" alt="enter image description here" /></a></p>