title: Will a readonly property with a custom getter have an instance variable synthesized?
body: <p>I have a situation where I don't want instance variables synthesized for a set of properties (I'm managing them via User Defaults and Keychain).</p>
  
  <p>If I have the following, <code>_loginUsername</code> will for sure be synthesized:</p>
  
  <pre><code>@property (nonatomic, readonly) NSString *loginUsername;
  </code></pre>
  
  <p>And I know if I had the following, an instance variable would not be synthesized, because the declaration is saying "I'm going to take care of it myself":</p>
  
  <pre><code>@property (nonatomic, getter = loginUsername, setter = setLoginUsername) NSString *loginUsername;
  </code></pre>
  
  <p>Is the behavior the same for a readonly property with a custom getter?:</p>
  
  <pre><code>@property (nonatomic, readonly, getter = loginUsername) NSString *loginUsername;
  </code></pre>
  
  <p>Will there be a <code>_loginUsername</code> synthesized for the final property declaration? I'm fairly sure that there won't, but I'm trying to get a better grasp of property attributes so want to make sure I'm not way off.</p>
  
  <p>Bonus points for explaining whether this is known at compile time (no cheating and checking in Xcode!).</p>
  
  <p>I don't have any <code>@synthesize</code> statements in my implementation file.</p>