title: ios swift, how to Convert NSMutableDictionary to nsdictionary
body: <p>i know obc is</p>
  
  <pre><code>NSMutableDictionary *mutableDict = [[[NSDictionary alloc] initWithObjectsAndKeys:
                                @"value", @"key"] mutableCopy];
  
  NSDictionary *dict = [NSDictionary dictionaryWithDictionary:mutableDict];
  </code></pre>
  
  <p>but swift,  how to Convert  NSMutableDictionary to nsdictionary</p>