An example of a programmatic custom view

ProfileInputField.swift

//
//  ProfileInputField.swift
//  CustomViews
//
//  Created by Daniel Esteban Cardona Rojas on 9/14/18.
//  Copyright © 2018 Daniel Esteban Cardona Rojas. All rights reserved.
//

import UIKit

protocol ProfileInputDelegate: class {
    func didTapEdit(_ input: ProfileInputField)
    func didTapSave(_ input: ProfileInputField)
}

class ProfileInputField: UIView {
    
    // MARK: - UI components, lazy instantiation
    lazy var titleLabel: UILabel = {
        let label = UILabel()
        let titleLabelFont = UIFont.systemFont(ofSize: 14)
        label.textAlignment = NSTextAlignment.left
        label.font = titleLabelFont
        label.translatesAutoresizingMaskIntoConstraints = false
        label.textColor = UIColor.hexStringToUIColor(hex: "#bebebe")
        return label
    }()
    
    lazy var inputField: UITextField = {
        let textField = UITextField()
        textField.textAlignment = NSTextAlignment.left
        textField.borderStyle = UITextBorderStyle.none
        textField.sizeToFit()
        textField.isEnabled = false
        textField.backgroundColor = .clear
        textField.translatesAutoresizingMaskIntoConstraints = false
        textField.textColor = UIColor.hexStringToUIColor(hex: UIConstants.kActionTextColor)
        return textField
    }()
    
    let editIcon: UIButton = {
        let button = UIButton(type: UIButtonType.custom)
        button.translatesAutoresizingMaskIntoConstraints = false
        button.contentMode = .scaleAspectFit
        return button
    }()
    
    // MARK: - Public API
    
    weak var delegate: ProfileInputDelegate?

    var isEditable: Bool = false {
        didSet {
            inputField.isEnabled = isEditable
            editIcon.isHidden = !isEditable
        }
    }
    
    var isPassword: Bool = false {
        didSet {
            inputField.isSecureTextEntry = isPassword
        }
    }
    
    var isEditing: Bool = false {
        didSet {
            let image = isEditing ? UIImage(named: "checkmark") : UIImage(named: "iconEdit")
            self.editIcon.setImage(image, for: .normal)
            self.inputField.isEnabled = isEditing
        }
    }
    
    public func configure(title: String, content: String) {
        titleLabel.text = title
        inputField.text = content
        isEditing = false
    }
    
    // MARK: - Overrides
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.commonInit()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.commonInit()
    }
    
    override var intrinsicContentSize: CGSize {
        return CGSize(width: 200, height: 66)
    }
    
    override func willMove(toSuperview newSuperview: UIView?) {
        super.willMove(toSuperview: newSuperview)
        commonInit()
    }
    
    
    // MARK: - Private
    private func commonInit() {
        translatesAutoresizingMaskIntoConstraints = false
        setContentCompressionResistancePriority(UILayoutPriorityDefaultHigh, for: .vertical)
        setContentCompressionResistancePriority(UILayoutPriorityDefaultLow, for: .horizontal)
        setupViews()
        setupContraints()
        setupActions()
    }
    
    private func setupViews() {
        self.addSubview(titleLabel)
        self.addSubview(inputField)
        self.addSubview(editIcon)
    }
    
    private func setupActions() {
        self.editIcon.addTarget(self, action: #selector(didTapEditButton(_:)), for: .touchUpInside)
    }
    
    
    // MARK: - Actions
    @objc func didTapEditButton(_ sender: Any) {
        self.editIcon.setImage(nil, for: .normal)
        isEditing = !isEditing
        
        if isEditing {
            self.inputField.becomeFirstResponder()
            self.delegate?.didTapEdit(self)
        } else {
            if self.inputField.isFirstResponder {
                self.inputField.resignFirstResponder()
            }
            self.delegate?.didTapSave(self)
        }
    }
    

    // MARK: Contraints
    private func setupContraints() {
        setupTitleLabelConstraints()
        setupTextFieldConstraints()
        setupEditIconConstraints()
    }
    
    private func setupTitleLabelConstraints() {
        NSLayoutConstraint.activate([
            titleLabel.leadingAnchor.constraint(equalTo: self.leadingAnchor),
            titleLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 10),
            titleLabel.heightAnchor.constraint(greaterThanOrEqualToConstant: 20),
            titleLabel.trailingAnchor.constraint(equalTo: editIcon.leadingAnchor, constant: -10)
            ])
    }
    
    private func setupTextFieldConstraints() {
        NSLayoutConstraint.activate([
            inputField.leadingAnchor.constraint(equalTo: self.leadingAnchor),
            inputField.topAnchor.constraint(greaterThanOrEqualTo: titleLabel.bottomAnchor, constant: 10),
            inputField.widthAnchor.constraint(equalTo: titleLabel.widthAnchor),
            inputField.heightAnchor.constraint(greaterThanOrEqualToConstant: 20),
            inputField.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: -10)
            ])
    }
    
    private func setupEditIconConstraints() {
        NSLayoutConstraint.activate([
            editIcon.leadingAnchor.constraint(equalTo: inputField.trailingAnchor, constant: 20),
            editIcon.trailingAnchor.constraint(equalTo: self.trailingAnchor),
            editIcon.centerYAnchor.constraint(equalTo: self.centerYAnchor),
            editIcon.widthAnchor.constraint(equalTo: editIcon.heightAnchor),
            editIcon.heightAnchor.constraint(equalTo: self.heightAnchor, multiplier: 0.3)
            ])
    }
    
    
}

extension ProfileInputField: UITextFieldDelegate {
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        log.debug("ShouldChangeTextfield")
        return true
    }
}