title: ScrollView is not working when try to add as a subview
body: <p>I have problems with my scrollView! I have a view called Rootview and I wanna add three subviews to a scrollview. When I add the scrollview as a subview the middle view and the three subviews disappear. This is my code.. The Rootview (whole window) and the scrollview are outlets.</p>
  
  <pre><code>UIView *middleView = [[UIView alloc] initWithFrame:CGRectMake(0, 218, 2024, 218)];
  [middleView setBackgroundColor: [UIColor yellowColor]];
  [RootView addSubview:middleView];
  
  //create new views for sap systems beginning from left
  
  UIView *firstSystem1 = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 300, 218)];
  [firstSystem1 setBackgroundColor: [UIColor grayColor]];
  [middleView addSubview:firstSystem1];
  
  UIView *secondSystem1 = [[UIView alloc] initWithFrame:CGRectMake(305, 0, 300, 218)];
  [secondSystem1 setBackgroundColor: [UIColor grayColor]];
  [middleView addSubview:secondSystem1];
  
  UIView *thirdSystem1 = [[UIView alloc] initWithFrame:CGRectMake(610, 0, 300, 218)];
  [thirdSystem1 setBackgroundColor: [UIColor grayColor]];
  [middleView addSubview:thirdSystem1];
  
  
  
  
  CGSize scrollViewContentSize1 = CGSizeMake(2024, 218);
  
   [middleScrollView setContentSize:scrollViewContentSize1];
  [middleScrollView addSubview:middleView];
  </code></pre>
  
  <p>Can anyone help me with that?</p>