How to bring a subview to front when selected in Swift? - swift

Question

So I've got two views, both added to the superview programmatically:
//First added view to my superView (baseView)
let imageViewOne = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
baseView.addSubview(imageViewOne)
//Second added view to my superView (baseView)
let imageViewTwo = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
baseView.addSubview(imageViewTwo)
I want to bring one of them to the front when it is selected because when you add a new view, it overlaps the previous one. Something that works with "selected" or "touched".

Answer 1

Use this:
baseView.bringSubview(toFront: imageViewOne)

Answer 2

You can do this by UITapGestureRecognizer by setting Restoration ID from the interface builder
func tapOneAct(sender: UITapGestureRecognizer) {
if(sender.view!.restorationIdentifier == "view1")
// view1 is `Restoration ID` of imageViewOne
{
view.bringSubview(toFront: imageViewOne)
}
if(sender.view!.restorationIdentifier == "view2")
// view2 is `Restoration ID` of 2nd view
{
view.bringSubview(toFront: imageViewTwo)
}
}

Answer 3

If I understand correctly then you would like to check the status of selected view and bring it to the front of the view hierarchy.
In this case you have to do following things:
1) track selection state, let it will be var isSelected: Bool in code snippet
2) hold a callback for an action when view is selected (you can use for example UIButton to observe tap event)
In following code snippet you can check the selection state when the view is touched.
BaseView implements logic for checking the state of SelectionView.
import UIKit
final class SelectionView<T: UIView>: UIView {
var onTap: ((_ isSelected: Bool) -> ())?
// MARK: - Private
private let view: T
private let button = UIButton(type: .custom)
private var isSelected: Bool = false
// MARK: - Init
init(view: T) {
self.view = view
super.init(frame: .zero)
setUp()
}
// MARK: - Private
private func setUp() {
addSubview(view)
addSubview(button)
button.addTarget(self, action: #selector(onButtonTap), for: .touchUpInside)
}
#objc private func onButtonTap() {
isSelected = !isSelected
onTap?(isSelected)
}
// MARK: - Layout
override func layoutSubviews() {
super.layoutSubviews()
view.frame = bounds
button.frame = bounds
}
override func sizeThatFits(_ size: CGSize) -> CGSize {
return view.sizeThatFits(size)
}
// MARK: - Unused
override init(frame: CGRect) {
fatalError("init(frame:) has not been implemented")
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
final class BaseView: UIView {
init() {
super.init(frame: .zero)
let views = [SelectionView(view: UIView()), SelectionView(view: UIView())]
for view in views {
view.onTap = { [weak self, weak view] isSelected in
guard let selectedView = view
else { return }
if isSelected {
self?.bringSubview(toFront: selectedView)
}
}
}
}
// MARK: - Unused
override init(frame: CGRect) {
fatalError("init(frame:) has not been implemented")
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}