How to make UIView fit the size of its contents?

I have the following code

 func setupUI() {
        self.view.backgroundColor = .white
        
        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);
        
        view.addSubview(titleLbl)
        
        // Using Auto Layout
        titleLbl.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            titleLbl.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            titleLbl.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 20),
            titleLbl.heightAnchor.constraint(equalToConstant: 20)
        ])
        
        innerView = UIView()
        innerView.backgroundColor = UIColor(red: 0.92, green: 0.96, blue: 0.99, alpha: 1.00)
        innerView.layer.cornerRadius = 12
        innerView.translatesAutoresizingMaskIntoConstraints = false
        self.view.addSubview(innerView)
        
        NSLayoutConstraint.activate([
            innerView.topAnchor.constraint(equalTo: titleLbl.bottomAnchor, constant: 40),
            innerView.heightAnchor.constraint(equalToConstant: 300),
            innerView.leadingAnchor.constraint(equalTo: self.view.leadingAnchor, constant: 20),
            innerView.trailingAnchor.constraint(equalTo: self.view.trailingAnchor, constant: -20)
        ])
        
        let backBtn = UIButton(frame: CGRect(x: self.view.frame.width - 60, y: 55, width: 40, height: 40))
        backBtn.setImage(UIImage.init(named: "close-circle"), for: .normal)
        backBtn.backgroundColor = UIColor.clear
        backBtn.addTarget(self, action: #selector(goback), for: .touchUpInside)
        self.view.addSubview(backBtn)

    
        let quote = self.book.quotes![self.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);
        
        innerView.addSubview(bodyLbl)
    
        
        // Using Auto Layout
        bodyLbl.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            bodyLbl.leadingAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.leadingAnchor, constant: 10),
            bodyLbl.topAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.topAnchor, constant: 20),
            bodyLbl.trailingAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.trailingAnchor, constant: -10)
        ])
        bodyLbl.sizeToFit()
        
        
        let shareButton = UIButton()
        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.isUserInteractionEnabled = true
        innerView.addSubview(shareButton)
        
        shareButton.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            shareButton.centerXAnchor.constraint(equalTo: innerView.centerXAnchor),
            shareButton.topAnchor.constraint(equalTo: bodyLbl.bottomAnchor, constant: 40),
            shareButton.heightAnchor.constraint(equalToConstant: 30),
            shareButton.widthAnchor.constraint(equalToConstant: 150)
        ])
        
        let count = self.book.quotes!.count
        if ((self.currentIndex + 1) > count) {
            self.nextBtn.isHidden = true
        } else {
            self.nextBtn.isHidden = false
        }
        
        innerView.setNeedsLayout()
        innerView.layoutIfNeeded()

        let newSize = innerView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
        innerView.frame.size = newSize
        innerView.sizeToFit()
    }

How can I make the innerView fit the size of it's contents? I set the height to 300 but I need it to fit the size of label and share button afterwards. Can someone help? What am I doing wrong? I tried sizeToFit but that doesn't work.

You can remove the constant height constraint, and add

shareButton.bottomAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.bottomAnchor, constant: -20)

With this constraint, there is now enough information for AutoLayout to determine the height of innerView, because it knows

• the top of bodyLbl is 20 pt below the top of innerView
• bodyLbl has an intrinsic height based on its content
• the top of shareButton is 40pt below the bottom of bodyLbl
• shareButton has a constant height of 30
• the bottom of shareButton is 20pt above the bottom of innerView

I'd also recommend using UIStackView for this kind of layout. You don't need to add any constraints to bodyLbl or shareButton - just do:

let stackView = UIStackView(arrangedSubviews: [bodyLbl, shareButton])
stackView.axis = .vertical
stackView.alignment = .center
stackView.setCustomSpacing(40, after: bodyLbl)
innerView.addSubview(stackView)

stackView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
    stackView.leadingAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.leadingAnchor, constant: 10),
    stackView.trailingAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.trailingAnchor, constant: -10),
    stackView.topAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.topAnchor, constant: 20),
    stackView.bottomAnchor.constraint(equalTo: innerView.safeAreaLayoutGuide.bottomAnchor, constant: -20),
    shareButton.heightAnchor.constraint(equalToConstant: 30),
    shareButton.widthAnchor.constraint(equalToConstant: 150)
])