title: Difference between _property and self.property
body: <p>I'm slightly confused as to the proper conventions when dealing with properties. I'll illustrate my question through an example. So from the example below I know that functionally "self.loan = self.loan + 250.00;" is the same as "_loan = _loan + 250.00;" or is it not? I see numerous tutorials all over the web that may or may not use both methods to access a property. So what exactly is the difference between using _loan and self.loan (I know that self.loan is the same as [self setLoan:])</p>
  
  <pre><code>//ClassA.h
  @interface ClassA: UIViewController
  @property double loan;
  @end
  
  //ClassA.m
  @implementation ClassA
  @synthesize loan = _loan;
  
  -(void)doSomething{
    self.loan = self.loan + 250.00; //Exhibit A
    _loan = _loan + 250.00; // Exhibit B 
  } 
  </code></pre>