title: Re-adding annotations on map view to update their title
body: <p>As you can see below, I have simulated my problem in a basic way. I have a timer that calls a method periodically.  In that method, I have created a switch-case condition to simulate my idea.</p>
  
  <p>Once pin is added on the map, then reading (pin keeps dropping) them again. </p>
  
  <p>I want to add my pin and then just only change the title that represents a weather value. </p>
  
  <pre><code>- (IBAction)playBtn:(id)sender {
  
       timer = [NSTimer scheduledTimerWithTimeInterval:(4.0) target:self selector:@selector(control) userInfo:nil repeats:YES];
  
  }
  
  -(void)control{
      NSMutableArray *annotationArray = [[[NSMutableArray alloc] init] autorelease];
  
      switch (value%2) {
          case 0:
          {
  
      // Create some annotations
      Annotation *annotation = nil;
  
      annotation = [[Annotation alloc] init];
      annotation.coordinate = CLLocationCoordinate2DMake(29.7161,-95.3906);
      annotation.color = RGB(13, 0, 182);
      annotation.title = @"17";
      [annotationArray addObject:annotation];
      [annotation release];
  
      annotation = [[Annotation alloc] init];
      annotation.coordinate = CLLocationCoordinate2DMake(30.168456,-95.504480);
      annotation.color = RGB(0, 182, 146);
      annotation.title = @"16";
      [annotationArray addObject:annotation];
      [annotation release];
  
  
      // Center map
      //self.mapView.visibleMapRect = [self makeMapRectWithAnnotations:annotationArray];
  
      // Add to map
      //[self.mapView addAnnotations:annotationArray];
          }
              break;
          case 1:
          {
              // Create some annotations
              Annotation *annotation = nil;
  
              annotation = [[Annotation alloc] init];
              annotation.coordinate = CLLocationCoordinate2DMake(29.7161,-95.3906);
              annotation.color = RGB(13, 0, 182);
              annotation.title = @"27";
              [annotationArray addObject:annotation];
              [annotation release];
  
              annotation = [[Annotation alloc] init];
              annotation.coordinate = CLLocationCoordinate2DMake(30.168456,-95.504480);
              annotation.color = RGB(0, 182, 146);
              annotation.title = @"25";
              [annotationArray addObject:annotation];
              [annotation release];
  
          }
              break;
      }
      [self.mapView addAnnotations:annotationArray];
      [mapView setNeedsDisplay];
      value++;
  </code></pre>