UITableView Section Header not showing

I'm trying to make section headers with autolayout. A simple header with a title and a counter

class ProfilePeopleListHeaderViewCell: UIView {

  let titleLeftOffset = 12
  let counterRightOffset = 5
  let counterWidth = 50

  var title = "title" {
    didSet {
      titleLabel.text = title
    }
  }
  var numberOfPeople = 0 {
    didSet {
      peopleCounter.text = "\(numberOfPeople)"
    }
  }

  let titleLabel = UILabel()
  let peopleCounter = UILabel()


  convenience init(title: String, numberOfPeople:Int) {
    self.init()
    self.title = title
    self.numberOfPeople = numberOfPeople
    backgroundColor = UIColor.greenColor()
    titleLabel.textColor = Constants.Colors.ThemeGreen
    titleLabel.textAlignment = .Left
    if #available(iOS 8.2, *) {
      titleLabel.font = Constants.Fonts.Profile.PeopleListHeaderFont
      peopleCounter.font = Constants.Fonts.Profile.PeopleListHeaderFont
    } else {
      titleLabel.font = UIFont.systemFontOfSize(14)
      peopleCounter.font = UIFont.systemFontOfSize(14)
    }

    peopleCounter.textAlignment = .Right
    peopleCounter.textColor = Constants.Colors.ThemeDarkGray

    addSubview(titleLabel)
    addSubview(peopleCounter)
    self.titleLabel.snp_makeConstraints { (make) -> Void in
      make.centerY.equalTo(self)
      make.height.equalTo(self)
      make.width.equalTo(peopleCounter).multipliedBy(3)
      make.left.equalTo(self).offset(titleLeftOffset)
    }

    self.peopleCounter.snp_makeConstraints { (make) -> Void in
      make.centerY.equalTo(self)
      make.height.equalTo(self)
      make.width.equalTo(counterWidth)
      make.left.equalTo(titleLabel.snp_right)
      make.right.equalTo(self).offset(counterRightOffset)
    }
  }

}

The code to retrieve the header is:

  let mutualFriendsSectionView = ProfilePeopleListHeaderViewCell(title: Strings.Title.MutualFriends, numberOfPeople: 0)

  override func tableView(tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
     if section == 1 {
        //mutualFriendsSectionView.layoutSubviews()
        return mutualFriendsSectionView
      }
  }

override func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
    return 40
    }

I get a green background in the section header. But I don't see any label...

Actually it's working. my mistake was to believe that didSet{} was also called within the class -> it's not the case.

When I was setting the title in the init() it was not setting the label text.