title: Cannot adjust UIScrollView with UITabbar
body: <p>i'm trying to setup a uiscrollview on a uinavigationbar and uitabbar controllers, the uiscrollview is limited to the bottom of the main view </p>
  
  <p>i tried to rewrite all of the constraints, and i've tried to add constant for the bottom constraint </p>
  
  <pre><code>// these are the constraints for the items inside the contentView 
  
  NSLayoutConstraint.activate([
              mainImg.topAnchor.constraint(equalTo: contentView.topAnchor),
              mainImg.rightAnchor.constraint(equalTo: contentView.rightAnchor),
              mainImg.leftAnchor.constraint(equalTo: contentView.leftAnchor),
              mainImg.bottomAnchor.constraint(equalTo: dateView.topAnchor),
  
  
              dateView.topAnchor.constraint(equalTo: mainImg.bottomAnchor),
              dateView.heightAnchor.constraint(equalToConstant: 40),
              dateView.rightAnchor.constraint(equalTo: contentView.rightAnchor),
              dateView.leftAnchor.constraint(equalTo: contentView.leftAnchor),
  
              calenderIcon.leadingAnchor.constraint(equalTo: dateView.leadingAnchor, constant: 20),
              calenderIcon.heightAnchor.constraint(equalToConstant: 20),
              calenderIcon.centerYAnchor.constraint(equalTo: dateView.centerYAnchor),
  
              dateLbl.leadingAnchor.constraint(equalTo: calenderIcon.trailingAnchor, constant: 10),
              dateLbl.centerYAnchor.constraint(equalTo: dateView.centerYAnchor),
  
              titleLbl.topAnchor.constraint(equalTo: dateView.bottomAnchor, constant: 18),
              titleLbl.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 24),
              titleLbl.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -24),
  
              articalLbl.topAnchor.constraint(equalTo: titleLbl.bottomAnchor, constant: 10),
              articalLbl.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 26),
              articalLbl.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -26),
              articalLbl.bottomAnchor.constraint(greaterThanOrEqualTo: contentView.bottomAnchor, constant: 100),
              articalLbl.heightAnchor.constraint(greaterThanOrEqualToConstant: 150)
  
  
          ])
  
  </code></pre>
  
  <pre><code>// this is the setup function for the scrollview
  
  func setupScrollView(){
          scrollView.translatesAutoresizingMaskIntoConstraints = false
          contentView.translatesAutoresizingMaskIntoConstraints = false
  
  
          view.addSubview(scrollView)
          scrollView.addSubview(contentView)
  
  
          scrollView.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
          scrollView.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
          scrollView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
          scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
  
          contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor).isActive = true
          contentView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true
          contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true
          contentView.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor).isActive = true
          contentView.centerYAnchor.constraint(equalTo: scrollView.centerYAnchor).isActive = true
  
      }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/uOy7y.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/uOy7y.png" alt="screenshot"></a></p>