title: the right operand of '-' is a garbage value
body: <p>I am using static analyzer for the first time and having difficulty to figure out the arrows. After looking some similar questions on S.O, I think the problem is the CGSize size is nil value but I am not entirely sure how its working.</p>
  
  <p>Here's the code:</p>
  
  <pre><code> - (void)keyboardDidShow:(NSNotification*)notification {
      CGSize size = CGSizeMake(0, 0);
      size = [self keyboardSize:notification];
        if (UIInterfaceOrientationIsLandscape(self.interfaceOrientation)) {
              detailTableView.frame = CGRectMake(detailTableView.frame.origin.x, detailTableView.frame.origin.y,
                                         detailTableView.frame.size.width, kTableViewMovableHeight + kTableViewDefaultHeight -  size.height
                                         );
      //detailTableView.scrollEnabled = YES;
      }
  }
  
  
  - (CGSize)keyboardSize:(NSNotification *)aNotification {
  NSDictionary *info = [aNotification userInfo];
  NSValue *beginValue = [info objectForKey:UIKeyboardFrameEndUserInfoKey];
  UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
  CGSize keyboardSize;
  UIDeviceOrientation _screenOrientation = orientation;
  if ([UIKeyboardDidShowNotification isEqualToString:[aNotification name]]) {
      if (UIDeviceOrientationIsPortrait(orientation)) {
          keyboardSize = [beginValue CGRectValue].size;
      } else {
          keyboardSize.height = [beginValue CGRectValue].size.width;
          keyboardSize.width = [beginValue CGRectValue].size.height;
      }
  } else if ([UIKeyboardWillHideNotification isEqualToString:[aNotification name]]) {
      if (_screenOrientation == orientation) {
          if (UIDeviceOrientationIsPortrait(orientation)) {
              keyboardSize = [beginValue CGRectValue].size;
          } else {
              keyboardSize.height = [beginValue CGRectValue].size.width;
              keyboardSize.width = [beginValue CGRectValue].size.height;
          }
          // rotated
      } else if (UIDeviceOrientationIsPortrait(orientation)) {
          keyboardSize.height = [beginValue CGRectValue].size.width;
          keyboardSize.width = [beginValue CGRectValue].size.height;
      } else {
          keyboardSize = [beginValue CGRectValue].size;
      }
  }
  return keyboardSize;
  }
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/x4O6k.png" alt="enter image description here"></p>