title: NSDictionary - Need to check whether dictionary contains key-value pair or not
body: <p>I just need to ask something as follow.
  Suppose I am having a dictionary.</p>
  
  <pre><code>NSMutableDictionary *xyz=[[NSMutableDictionary alloc] init];
  [xyz setValue:@"sagar" forKey:@"s"];
  [xyz setValue:@"amit" forKey:@"a"];
  [xyz setValue:@"nirav" forKey:@"n"];
  [xyz setValue:@"abhishek" forKey:@"a"];
  [xyz setValue:@"xrox" forKey:@"x"];
  </code></pre>
  
  <p>Now, I need to check as follows</p>
  
  <p>[xyz does contains key "b" value ?? pair or not?</p>
  
  <p>Question is How? </p>
  
  <p>The other question is How to just count total key-value pair?</p>
  
  <p>Say for example <code>NSInteger mCount=[xyz keyCounts];</code></p>