title: What is the difference between (+) and (-) operator in obj c function
body: <p>Hi i am new to iphone and starts to learning Obj c.</p>
  
  <p>i have notice the function definition, for some function we are using (-) and for some function we are using (+) </p>
  
  <p>Example:
  + (id)requestWithURL:(NSURL *)theURL</p>
  
  <p>– initWithURL:</p>
  
  <p>what the difference between those two operator / symbol's usage?</p>
  
  <p>thanks!</p>