title: Explaining apples documentation
body: <p>I'm trying to understand this two parameters of the method but i don't seems to understand it.
  <code>addObserverForName:object:queue:usingBlock:</code></p>
  
  <p>I don't understand the description of 2 of the parameters in the method. Hope someone can explain it to me.</p>
  
  <p><code>- (id)addObserverForName:(NSString *)name object:(id)obj queue:(NSOperationQueue *)queue usingBlock:(void (^)(NSNotification *))block</code></p>
  
  <p>I don't understand this 2 lines:</p>
  
  <blockquote>
    <p><strong>name</strong>
    The name of the notification for which to register the observer; that is, only notifications with this name are used to add the block to the operation queue.
    If you pass nil, the notification center doesn’t use a notification’s name to decide whether to add the block to the operation queue.</p>
  </blockquote>
  
  <p>what does it mean when the notification centre doesn't use notification name to decide whether to add block to the operation queue when it is nilled.
  also,what notification name should i put in. I don't know.
  and</p>
  
  <blockquote>
    <p><strong>obj</strong>
    The object whose notifications you want to add the block to the operation queue.
    If you pass nil, the notification center doesn’t use a notification’s sender to decide whether to add the block to the operation queue.</p>
  </blockquote>
  
  <p>What object should i insert into this parameters.</p>