RoundedBorderButton.swift

RoundedBorderButton.swift

import UIKit

@IBDesignable
class RoundedBorderButton: UIButton {

    @IBInspectable dynamic var cornerRadius: CGFloat = 20.0 {
        didSet {
            layer.cornerRadius = cornerRadius
            layer.masksToBounds = true
        }
    }
    @IBInspectable dynamic var borderWidth: CGFloat = 1.0 {
        didSet {
            layer.borderWidth = borderWidth
        }
    }
    @IBInspectable dynamic var verticalInset: CGFloat = 10.0 {
        didSet {
            contentEdgeInsets.top = verticalInset
            contentEdgeInsets.bottom = verticalInset
        }
    }
    @IBInspectable dynamic var horizontalInset: CGFloat = 20.0 {
        didSet {
            contentEdgeInsets.left = horizontalInset
            contentEdgeInsets.right = horizontalInset
        }
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        _init()
    }
    override init(frame: CGRect) {
        super.init(frame: frame)
        _init()
    }
    func _init() {
        clipsToBounds = true
        layer.borderColor = titleColor(for: .normal)?.cgColor
        setTitleColor(titleColor(for: .normal)?.withAlphaComponent(highlightedAlpha), for: .highlighted)
        
        // repeat all didSets so that defaults are applied
        layer.cornerRadius = cornerRadius
        layer.borderWidth = borderWidth
        contentEdgeInsets.top = verticalInset
        contentEdgeInsets.bottom = verticalInset
        contentEdgeInsets.left = horizontalInset
        contentEdgeInsets.right = horizontalInset
    }

    private var normalAlpha: CGFloat = 1
    private var highlightedAlpha: CGFloat = 0.2
    private var borderColorAlpha: CGFloat? {
        get {
            return layer.borderColor?.alpha
        }
        set {
            if let borderColor = layer.borderColor,
               let newAlpha = newValue {
                layer.borderColor = UIColor(cgColor: borderColor).withAlphaComponent(CGFloat(newAlpha)).cgColor
            }
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        if borderWidth > 0 {
            if state == .highlighted && borderColorAlpha != highlightedAlpha {
                borderColorAlpha = highlightedAlpha
                layoutIfNeeded()
            } else if state == .normal && borderColorAlpha != normalAlpha {
                borderColorAlpha = normalAlpha
                layoutIfNeeded()
            }
        }
    }
}