Design System

Design.swift

extension UIButton {
    private func actionHandler(action:(() -> Void)? = nil) {
        struct HandlerStruct { static var action :(() -> Void)? }
        
        if action != nil {
            HandlerStruct.action = action
        } else { HandlerStruct.action?() }
    }
    
    @objc private func triggerActionHandler() {
        self.actionHandler()
    }
    
    func actionHandler(controlEvents control: UIControl.Event, forAction action: @escaping () -> Void) {
        self.actionHandler(action: action)
        self.addTarget(self, action: #selector(triggerActionHandler), for: control)
    }
}



public struct Design {
    
}


extension Design {
    public struct Button {
        public static let primaryButton: ContentStyle<UIButton> = { button in
            button.backgroundColor = .systemBlue
            button.tintColor = .white
            button.layer.cornerRadius = ConerRadius.size(.small)()
        }
        
        public static let dangerButton: ContentStyle<UIButton> = { button in
            button.setTitleColor(.red, for: .normal)
            button.layer.cornerRadius = ConerRadius.size(.small)()
            button.layer.borderWidth = 1
            button.layer.borderColor = UIColor.red.cgColor
            button.backgroundColor = UIColor.red.withAlphaComponent(0.05)
        }
        
        public static let secondaryButton: ContentStyle<UIButton> = { button in
            button.backgroundColor = .clear
            button.tintColor = .blue
            button.layer.cornerRadius = ConerRadius.size(.small)()
            button.layer.borderWidth = 1
            button.layer.borderColor = UIColor.blue.cgColor
        }

        public enum Design {
            case primary
            case secondary
            case danger
        }
    }
    
}



extension Design {
    
    public struct Label {
        public static let heading: ContentStyle<UILabel> = { label in
            label.font = .preferredFont(forTextStyle: .body)

        }
    }
    
}



extension Design {
    public enum ConerRadius {
        case small
        case medium
        case big
        
        fileprivate func size() -> CGFloat {
            switch self {
            case .small:
                return 8
            case .medium:
                return 16
            case .big:
                return 32
            }
        }
    }
}

class View: UIView {
    
    public var cornerRadius : Design.ConerRadius? {
        didSet(value) {
            guard let r = cornerRadius else { return }
            layer.cornerRadius = r.size()
        }
    }
    
    override init(frame: CGRect) {
        super.init(frame: frame)
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}


public typealias ContentStyle<Content> = (Content) -> Void

class Button: UIButton {
    
    public var style : Design.Button.Design? {
        didSet(value) {
            applayStyle()
        }
    }

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    init(style: Design.Button.Design) {
        super.init(frame: .zero)
        self.style = style
        self.applayStyle()
    }
    
    private func applayStyle() {
        switch style {
        case .primary:
            Design.Button.primaryButton(self)
        case .danger:
            Design.Button.dangerButton(self)
        case .secondary:
            Design.Button.secondaryButton(self)

        case .none:
            print("=--")
        }
    }
}


extension Design {
    struct Color {
        public static let primary: ContentStyle<UIColor> = { color in
            
        }
        
        public static let accent: ContentStyle<UIColor> = { color in
        
        }
        
        public static let seconary: ContentStyle<UIColor> = { color in
        
        }
    }
}


/// Usage: 
class ViewController: UIViewController {
    
 //    @IBOutlet weak var backView: View!
 //    @IBOutlet weak var button: Button!
 //
    lazy var danger: Button = {
        let btn = Button(style: .danger)
        btn.setTitle("HOME", for: .normal)
        btn.translatesAutoresizingMaskIntoConstraints = false
        return btn
    }()
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.addSubview(danger)
        
        danger.bottomAnchor.constraint(equalTo: self.view.bottomAnchor, constant: -100).isActive = true
        danger.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
        danger.widthAnchor.constraint(equalToConstant: 100).isActive = true
        danger.heightAnchor.constraint(equalToConstant: 54).isActive = true
//        backView.cornerRadius = .big
//        button.style = .secondary
    }
}