title: Removing negative numbers from NSArray in Objective C
body: <p>I am new to Objective C. In my application, I am having array of data, in which I need only positive numbers and need to delete negative numbers. </p>
  
  <pre><code>result = [NSMutableArray arrayWithObjects: @"1",@"2",@"3","-4","-5","6","9",nil];
  NSLog(@"  Before Remove  %d", [result count]);
  NSString *nullStr = @"-";
  [result removeObject:nullStr];
  </code></pre>
  
  <p>How to achieve this? Any pointers?</p>