create UITableViewCell constraint programmatically

you should be adding your constraints in init for the cell, assuming it will be a dequeued reusable cell, remember to use contentView instead of View for the bounds of the cell:

class CustomCell2: UITableViewCell {

//MARK: Subviews
//Add View Programmatically or in xib
let titleLabel: UILabel = {
    let label = UILabel()
    label.text = " Title "
    //…
    label.translatesAutoresizingMaskIntoConstraints = false //Must use
    return label
}()

//…


//MARK: init
//Add Subviews and then layout Contraints to the Cell’s contentView
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
    super.init(style: style, reuseIdentifier: reuseIdentifier)
    addSubViewsAndlayout()
}



/// Add and sets up subviews with programmically added constraints
func addSubViewsAndlayout() {
    contentView.addSubview(titleLabel) //will crash if not added

    let screenwidth = UIScreen.main.bounds.width //get any other properties you need

    titleLabel.topAnchor.constraint(equalTo: self.contentView.topAnchor, constant: 12.0).isActive = true
    titleLabel.heightAnchor.constraint(equalToConstant: 30).isActive = true
    titleLabel.leftAnchor.constraint(equalTo: self.contentView.leftAnchor, constant: 12).isActive = true
    titleLabel.rightAnchor.constraint(equalTo: otherViewToTheSide.rightAnchor, constant: -24).isActive = true 

//...

I also like to implement the following methods instead of using hard coded values / strings.

/// Get the Height of the cell
/// use this in heightForRowAt indexPath
/// - Returns: CGFloat
class func height() -> CGFloat {
    return 175
}
//CustomCell2.height()


/// Get the string identifier for this class.
///
/// - Retruns: String
class var identifier: String {
    return NSStringFromClass(self).components(separatedBy: ".").last!
}
//use when registering cell:
self.tableView.register(CustomCell2.self, forCellReuseIdentifier: CustomCell2.identifier)

You can create UITableViewCell constraint Programatically like :

class ViewController: UITableViewController {

override func viewDidLoad() {
    super.viewDidLoad()
    tableView.register(CustomCell2.self, forCellReuseIdentifier: "cell")
}

override func numberOfSections(in tableView: UITableView) -> Int {
    return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 2
}

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    guard let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as? CustomCell2 else { return UITableViewCell() }
    cell.model = CellModel(labelString: "set constriant by code")
    return cell
}  
}

Define Model :

struct CellModel {
let labelString : String
}

Define custom Cell :

class CustomCell2 : UITableViewCell {
private let label : UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false // enable auto-layout
    label.backgroundColor = .green // to visualize 
    label.textAlignment = .center // text alignment in center
    return label
}()

private func addLabel() {
    addSubview(label)
    NSLayoutConstraint.activate([
        // label width is 70% width of cell
        label.widthAnchor.constraint(equalTo: widthAnchor, multiplier: 0.7),
        // center along horizontally 
        label.centerXAnchor.constraint(equalTo: centerXAnchor)
    ])
}

var model : CellModel? {
    didSet {
        label.text = model?.labelString ?? "Test"
    }
}

// Init 
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
    super.init(style: style, reuseIdentifier: reuseIdentifier)
    addLabel()
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
} 
}

Output