How to position subview below left bottom corner of a button in view controller?

Question

I have an options button (that 3 vertical dotted button) on top of the view controller. When I click that button, A list view should appear like in many other apps like WhatsApp... I really don't know how to position it always near to the button programmatically.

Answer 1

Placing at the left-bottom of an existing view is quite easier:

func placeSubView(existingView: UIView)
{
    let desiredWidth = CGFloat(50.0)
    let desiredHeight = CGFloat(35.0)
    let (x, y) = (existingView.frame.origin.x - desiredWidth, existingView.frame.origin.y + existingView.frame.size.height)

    let desiredView = UIView(frame: CGRect(x: x, y: y, width: desiredWidth, height: desiredHeight))

    existingView.superview?.addSubview(desiredView)
}

UPDATE:

In case you are looking for popupo menu like view, you should search about UIPopoverPresentationController.

Something like this.

Answer 2

Use this method and make PopoverViewController a table view controller if you want a list.

@IBAction func displayPopover(_ sender: UIBarButtonItem) {
    let storyboard : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let vc = storyboard.instantiateViewController(withIdentifier: "PopoverViewController")
    vc.modalPresentationStyle = .popover
    let popover: UIPopoverPresentationController = vc.popoverPresentationController!
    popover.barButtonItem = sender
    present(vc, animated: true, completion:nil)
}