Code snippets for blog "Touchy-feely"

button-subview.swift

class Button: UIButton {
    private var tappableSurface: UIButton?
    
    override func addTarget(_ target: Any?, action: Selector, for controlEvents: UIControlEvents) {
        super.addTarget(target, action: action, for: controlEvents)

        if bounds.size.width < .minimumButtonDimension || bounds.size.height < .minimumButtonDimension {
            let button = UIButton()
            
            addSubview(button)
            sendSubview(toBack: button)
            
            button.translatesAutoresizingMaskIntoConstraints = false
            button.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
            button.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
            button.widthAnchor.constraint  (equalToConstant: max(bounds.size.width,  .minimumButtonDimension)).isActive = true
            button.heightAnchor.constraint (equalToConstant: max(bounds.size.height, .minimumButtonDimension)).isActive = true
            
            button.addTarget(target, action: action, for: controlEvents)
            
            tappableSurface = button
        }
    }
}

private extension CGFloat {
    static let minimumButtonDimension: CGFloat = 44.0
}

extended-button.swift

class Button: UIButton, ExtendedTouchable {
    var touchableSurface: UIView?
    
    override func layoutSubviews() {
        super.layoutSubviews()
        setupTouchableArea()
    }
}

extended-touchable.swift

protocol ExtendedTouchable: class {
    var touchableSurface: UIView? { get set }
    func setupTouchableArea()
}

extension ExtendedTouchable where Self: UIControl {
    func setupTouchableArea() {
        touchableSurface = {
            let view = UIView()
            
            view.backgroundColor = .clear
            addSubview(view)
            sendSubview(toBack: view)

            view.translatesAutoresizingMaskIntoConstraints = false
            view.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
            view.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
            view.widthAnchor.constraint  (equalToConstant: max(bounds.size.width,  .minimumButtonDimension)).isActive = true
            view.heightAnchor.constraint (equalToConstant: max(bounds.size.height, .minimumButtonDimension)).isActive = true

            return view
        }()
    }
}

hit-test.swift

class Button: UIButton, ExtendedTouchable {
    var touchableSurface: UIView?
    
    override func layoutSubviews() {
        super.layoutSubviews()
        setupTouchableArea()
    }
    
    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        guard let touchableSurface = touchableSurface, touchableSurface.frame.contains(point) else {
            return super.hitTest(point, with: event)
        }
        
        return self
    }
}

Touchy Feely.md

Code snippets for the blog post "Touchy Feely" http://www.apokrupto.com/blog-1/2017/2/11/touchy-feely