ios – How to make UIView fit the size of its contents?

Make the height implied by its contents: remove the fixed height, and fully constrain the content from top → bottom inside innerView. Also don’t fix titleLbl’s height.

func setupUI() {
    view.backgroundColor = .white

    // Title
    let titleLbl = UILabel()
    titleLbl.text = book.title
    titleLbl.textColor = .black
    titleLbl.textAlignment = .center
    titleLbl.numberOfLines = 0
    titleLbl.lineBreakMode = .byWordWrapping
    titleLbl.font = UIFont(name: "Inter-Regular", size: 16)

    titleLbl.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(titleLbl)

    NSLayoutConstraint.activate([
        titleLbl.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 20),
        titleLbl.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
        titleLbl.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20)
        // ❌ no fixed height — let it wrap
    ])

    // Close button (use constraints instead of frames)
    let backBtn = UIButton(type: .system)
    backBtn.setImage(UIImage(named: "close-circle"), for: .normal)
    backBtn.tintColor = .black
    backBtn.backgroundColor = .clear
    backBtn.addTarget(self, action: #selector(goback), for: .touchUpInside)
    backBtn.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(backBtn)

    NSLayoutConstraint.activate([
        backBtn.centerYAnchor.constraint(equalTo: titleLbl.centerYAnchor),
        backBtn.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -16),
        backBtn.widthAnchor.constraint(equalToConstant: 40),
        backBtn.heightAnchor.constraint(equalToConstant: 40)
    ])

    // Container
    let innerView = UIView()
    self.innerView = innerView
    innerView.backgroundColor = UIColor(red: 0.92, green: 0.96, blue: 0.99, alpha: 1.0)
    innerView.layer.cornerRadius = 12
    innerView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(innerView)

    NSLayoutConstraint.activate([
        innerView.topAnchor.constraint(equalTo: titleLbl.bottomAnchor, constant: 24),
        innerView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
        innerView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20)
        // ❌ no fixed height here
    ])

    // Body label
    let quote = book.quotes![currentIndex]
    let bodyLbl = UILabel()
    bodyLbl.text = quote
    bodyLbl.textColor = .black
    bodyLbl.textAlignment = .center
    bodyLbl.numberOfLines = 0
    bodyLbl.lineBreakMode = .byWordWrapping
    bodyLbl.font = UIFont(name: "Inter-Regular", size: 16)
    bodyLbl.translatesAutoresizingMaskIntoConstraints = false
    innerView.addSubview(bodyLbl)

    NSLayoutConstraint.activate([
        bodyLbl.topAnchor.constraint(equalTo: innerView.topAnchor, constant: 20),
        bodyLbl.leadingAnchor.constraint(equalTo: innerView.leadingAnchor, constant: 12),
        bodyLbl.trailingAnchor.constraint(equalTo: innerView.trailingAnchor, constant: -12)
    ])

    // Share button
    let shareButton = UIButton(type: .system)
    shareButton.setTitle("Share", for: .normal)
    shareButton.setTitleColor(.white, for: .normal)
    shareButton.backgroundColor = .black
    shareButton.addTarget(self, action: #selector(self.share), for: .touchUpInside)
    shareButton.layer.cornerRadius = 12
    shareButton.clipsToBounds = true
    shareButton.translatesAutoresizingMaskIntoConstraints = false
    innerView.addSubview(shareButton)

    NSLayoutConstraint.activate([
        shareButton.centerXAnchor.constraint(equalTo: innerView.centerXAnchor),
        shareButton.topAnchor.constraint(equalTo: bodyLbl.bottomAnchor, constant: 24),
        shareButton.heightAnchor.constraint(equalToConstant: 36),
        shareButton.widthAnchor.constraint(equalToConstant: 150),

        // 👇 This is the key: pin the last subview to the bottom
        innerView.bottomAnchor.constraint(equalTo: shareButton.bottomAnchor, constant: 20)
    ])

    // Next button visibility (logic bug fix)
    let count = book.quotes!.count
    nextBtn.isHidden = (currentIndex + 1) >= count
}