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Nguyen Truong Ky
Nguyen Truong Ky

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UI Implementation - Confirmation popup

In previous post, I shared you how to show an animated popup, and explained how to customize your popup. In this post, I share how I use the popup in my projects with confirmation and information alert.
An information popup is used to alert user about some important information, like this

A confirmation alert is very useful to warn user about next action, for instance, confirm to remove a photo, confirm a withdrawal request… In this post, I will extend the knPopup to knConfirmation to display a confirmation popup.

The idea is same to the previous post, you can customize any UI you want in setupView.

Define new controls

class knConfirmation: knPopup {
    private let iconImgView = UIMaker.makeImageView()
    let titleLabel = UIMaker.makeLabel(font: UIFont.boldSystemFont(ofSize: 18),
                                    color: UIColor.darkGray, numberOfLines: 2,
                                    alignment: .center)
    let contentLabel = UIMaker.makeLabel(font: UIFont.systemFont(ofSize: 15),
                                    color: UIColor.lightGray, numberOfLines: 0,
                                    alignment: .center)
    private let stack = UIMaker.makeStackView()
    private let cancelButton = UIMaker.makeButton(titleColor: .darkGray,
                                        font: UIFont.systemFont(ofSize: 15),
                                        cornerRadius: 27,
                                        borderWidth: 1,
                                        borderColor: .darkGray)
    private let buttonStack = UIMaker.makeStackView(axis: .horizontal, distributon: UIStackView.Distribution.fill, alignment: UIStackView.Alignment.fill, space: 16)

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)

A confirmation popup needs:

  • 1 icon (optional)
  • 2 labels: title (optional), content
  • 2 buttons: 1 for accept action, 1 for reject action (optional). We have okButton in knPopup, just need one more for reject action
  • 2 stack views: 1 to contain 2 buttons, 1 to contain all controls

Layout the view

We will setup auto layout for all controls by code in setupView function

override func setupView() {
    // (1)
    buttonStack.addViews(cancelButton, okButton)
    cancelButton.size(toView: okButton)
    okButton.vertical(toView: buttonStack)
    cancelButton.centerY(toView: okButton)

    // (2)
    let spaceView = UIMaker.makeView()

    stack.addViews(iconImgView, titleLabel, contentLabel, spaceView, buttonStack)
    iconImgView.square(edge: 56)
    iconImgView.centerX(toView: stack)
    titleLabel.horizontal(toView: stack, space: 16)
    contentLabel.horizontal(toView: stack, space: 16)
    buttonStack.horizontal(toView: stack, space: 16)

    // (3)
    stack.fill(toView: container, space: UIEdgeInsets(top: 16, bottom: 16))

    okButton.addTarget(self, action: #selector(didSelectOK), for: .touchUpInside)
    cancelButton.addTarget(self, action: #selector(dismiss), for: .touchUpInside)


  • buttonStack is a UIStackView, so we can’t addSubviews as usual, but have to addArrangedSubview. I extend to new function addViews to shorten the name. :)
  • buttonStack contains the button, so when you don’t need cancel button, you can remove it from buttonStack, and okButton automatically fill the superView. That’s why I choose UIStackView for this UI.


  • In stackView, you can’t change specific space between 2 views, so I did this trick. Insert a space view with a height I want.


  • We need to add stack to container. The container is setup to animate when appear/disappear. So we don’t need to care about animation anymore.

Dynamically display what you want

Some popups, you need to show an icon to make it be colorful. Others don’t need title and cancel button. We will dynamically init what we want.

init(icon: UIImage? = nil, title: String? = nil, content: String, okTitle: String? = nil, cancelTitle: String? = nil) {
    super.init(frame: .zero)
    set(icon: icon, title: title, content: content, okTitle: okTitle, cancelTitle: cancelTitle)

private func set(icon: UIImage? = nil, title: String? = nil, content: String, okTitle: String? = nil, cancelTitle: String? = nil) {
    if icon == nil {
    } else {
        iconImgView.image = icon

    if title == nil {
    } else {
        titleLabel.text = title

    contentLabel.text = content
    if okTitle != nil {
        okButton.setTitle(okTitle, for: .normal)

    if cancelTitle == nil {
    } else {
        cancelButton.setTitle(cancelTitle, for: .normal)

Just pass nil or remove that param from the init function. What param is nil, the related control will be removed from UI.

Run the app

Live sample


Hope this popup can help you save your time and efforts to display a popup. Customize what you want and share it to me via this repository.

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